Contains Class definitions of several Standard Controls used in the Lazarus IDE Custom Scroll Bar Custom Scroll Bar: the base type from which Control Bars are derived TCustomScrollBar constructor TCustomScrollBar constructor - override definition, so supplied method can supersede any inherited method. It sets up a few defaults which can be modified by the application programmer Defines the Max and Min values, the size of the page and the position of the scroller Whether Horizontal or Vertical The size of the step to be taken by the scroller for a large change A large change is produced by the user clicking on the blank are above or below the scroller; it is rather analogous to the Page Down or Page Up functions of the Keyboard and typically moves the scroller and the contents of the page or canvas by a whole paragralph or half a page or a full page. The maximum value (for bottom of the scroll bar or the right-most extent) the minimum value, for the top of the scroll bar or its left-most extent the size of the page on which this scrollbar is found The position of the scrollbar on the current page The size of the step to be taken by the scroller for a small change A small change is produced by the user clicking on one of the triangular tags at either end of the scrollbar. It is rather analogous to the effet of using the up or down arrows on the keyboard, and typically produces a movement of a few pixels or a single line of text Whether the scrollbar can be reached by use of the Tab key - default is True Event handler for any change in position of the scroller or other mouse movement or keyboard event associated with the scrollbar Handler for a scrolling event Scroll Bar Scroll Bar for Text Box or Memo. Can be none, horizontal, vertical or both. May appear automatically when the text goes outside the window.
Scroll codes may be line up or down, page up or down, track the mouse, top of panel, bottom of panel, or end scroll.

Inherits several properties from ancestor classes, and many properties can be adjusted with the Object Inspector and the Form Designer Custom Group Box Custom Group Box: the base type from which Group Box and related components are derived. Group Box Group Box. Allows a number of objects to be grouped physically and conceptually on the form; they can be moved around together and have certain properties in common.
They share the same scope for several variables, which are hidden from objects outside the group.
They can interact with one another, for example radio buttons will be mutually exclusive within the group. TComboBoxAutoCompleteTextOption defines the behavior of the AutoComplete feature in a combobox control. TComboBoxAutoCompleteTextOption = (cbactEnabled, cbactEndOfLineComplete, cbactRetainPrefixCase, cbactSearchCaseSensitive, cbactSearchAscending); Defines the behavior of the AutoComplete feature. <ul><li>cbactEnabled: Enable Auto-Completion feature.</li><li>cbactEndOfLineComplete: Perform Auto-Complete only when cursor is at the end of the string.</li><li>cbactRetainPrefixCase: Retains the case of characters user has typed. (This option has no effect if cbactEndOfLineComplete is False)</li><li>cbactSearchCaseSensitive: Search completion string with case sensitivity.</li><li>cbactSearchAscending: Search completion string in accending order. (False will search in descending order)</li></ul> TComboBoxAutoCompleteText = set of TComboBoxAutoCompleteTextOption; <link id="TComboBoxAutoCompleteTextOption"/> ComboBox Style ComboBox Style: may be Simple, a Drop-Down or a drop-down list, or some version drawn by the Owner Custom Combo Box Custom Combination Box: the base class from which Combo Box is derived. FCharCase: TEditCharCase FAutoCompleteText: TComboBoxAutoCompleteText Private variable of property AutoCompleteText. Options for behavior of the Auto-Complete feature. FAutoSelect: Boolean Private variable for property AutoSelect. When True, the edit control will select all its text when: <ul><li>It recieves focus</li><li>The Enter key is pressed.</li><li>A new item is selected.</li></ul> FAutoSelected: Boolean Private variable for property AutoSelected. True indicate that the edit or combobox control has just performed an AutoSelect opertation so that subsequent mouse-clicks and keystrokes proceeds normally without selecting the text. False is set when the edit or combobox control looses focus. Combo Box Combo box. A simple combination of text box for free text entry, and a drop-down list allowing one of several options to be chosen. property CharCase: TEditCharCase Indicates how text is displayed in a text editing control in the following ways: <ul><li>Normal case letters</li><li>Upper case letters</li><li>Lower case letters</li></ul> property AutoCompleteText: TComboBoxAutoCompleteText Options for behavior of the Auto-Complete feature. <link id="TComboBoxAutoCompleteTextOption"/> property AutoSelect: Boolean When True, the edit control will select all its text when: <ul><li>It recieves focus</li><li>The Enter key is pressed.</li><li>A new item is selected.</li></ul> property AutoSelected: Boolean True indicate that the edit or combobox control has just performed an AutoSelect operation so that subsequent mouse-clicks and keystrokes proceeds normally without selecting the text. False is set when the edit or combobox control looses focus. Combo Box Combo box. A simple combination of text box for free text entry, and a drop-down list allowing one of several options to be chosen. property AutoComplete: Boolean True: Turns on auto-complete feature. False: Turns off auto-complete feature. property AutoCompleteText: TComboBoxAutoCompleteText Options for behavior of the Auto-Complete feature. <link id="TComboBoxAutoCompleteTextOption"/> <link id="TComboBoxAutoCompleteText"/> property AutoSelected: Boolean When True, the edit control will select all its text when: <ul><li>It recieves focus</li><li>The Enter key is pressed.</li><li>A new item is selected.</li></ul> property CharCase: TEditCharCase Indicates how text is displayed in a text editing control in the following ways: <ul><li>Normal case letters</li><li>Upper case letters</li><li>Lower case letters</li></ul> Options for behavior of the Auto-Complete feature. <link id="TComboBoxAutoCompleteTextOption"/><link id="TComboBoxAutoCompleteText"/> Custom List Box Custom List Box: the base type from which List Box is derived. List Box List Box: a simple drop-down list from which a choice is made Determines the case of text displayed in the edit box or combobox. Character case according to what the user types. Converts every character that the user types into upper case characters. Converts every character that the user types into lower case characters. TEchoMode: Determines how strings in the edit box is displayed. Custom Edit Custom Edit: the base type from which Edit Box is derived. FAutoSelect: Boolean Private variable for property AutoSelect. When True, the edit control will select all its text when: <ul><li>It recieves focus</li><li>The Enter key is pressed.</li><li>A new item is selected.</li></ul> FAutoSelected: Boolean Private variable for property AutoSelected. True indicate that the edit or combobox control has just performed an AutoSelect opertation so that subsequent mouse-clicks and keystrokes proceeds normally without selecting the text. False is set when the edit or combobox control looses focus. FCharCase: TEditCharCase Private variable for property CharCase. Indicates how text is displayed in a text editing control in the following ways: <ul><li>Normal case letters</li><li>Upper case letters</li><li>Lower case letters</li></ul> <link id="TEditCharCase"/><link id="TEditCharCase.ecNormal"/><link id="TEditCharCase.ecUppercase"/><link id="TEditCharCase.ecLowerCase"/> property AutoSelect: Boolean When True, the edit control will select all its text when it recieves focus or when the Enter key is pressed. property AutoSelected: Boolean True indicate that the edit or combobox control has just performed an AutoSelect operation so that subsequent mouse-clicks and keystrokes proceeds normally without selecting the text. False is set when the edit or combobox control looses focus. CustomEdit constructor CustomEdit constructor, supplied code will override declarations by ancestor classes Selects all text in buffer, in preparation for an operation such as Copy or Clear Clears selected portion of Text Copies selected text to the clipboard Cuts selected text (ie removes it) and stores it in the clipboard Pastes the contents of the clipboard into the current position in Text property CharCase: TEditCharCase Indicates how text is displayed in a text editing control in the following ways: <ul><li>Normal case letters</li><li>Upper case letters</li><li>Lower case letters</li></ul> EchoMode: how the typed characters are to appear on the screen EchoMode: can be None (no character appears); Normal (the character typed is shown directly); Password (a series of *** or other chosen characters are displayed instead of the typed characters).
Reads or writes a flag to determine the mode
Default is normal Max Length Max Length: maximum length allowed for text string Modified Modified: has the text been modified since creation? Password Character Password Character: the character which appears in the Edit box replacing and masking the actual character typed. Typically used in password input, to prevent the typed characters from being seen by passers-by or casual observers (or even malicious observers!) Sel Length Sel Length: the length (in characters) of the text that has been selected for editing Sel Start Sel Start: the index of the character from which selection (for editing) begins Sel Text Sel Text: the text of the actual string that has been selected for editing Text: the character string contained in the Edit Box Most of the operations (such as Select, Clear, Cut, Copy are performed in this part of the object, which holds the actual string being edited Custom Memo Custom Memo: the base type from which Memo is derived CustomMemo constructor CustomMemo constructor. Supplied code will override definition in ancestor classes CustomMemo destructor CustomMemo destructor. Supplied code will override definitions from ancestor classes Append a line of text to the CustomMemo Append a line of text to the CustomMemo. The Value is an explicit string to be passed to the procedure for insertion at the end of the text buffer Lines Value: the string to be added to Lines Lines Lines: an array of strings (representing single lines of characters) which contains the textual material held or being entered in the Memo. Word Wrap Word Wrap: a logical flag to show whether or not word-wrap is enabled, ie if a word nears the end of a line and is going to be too long for the line, it is wrapped down to the next line Edit Box Edit Box: for entry or display of a single line of text.
Inherits most of its properties from TCustomEdit property AutoSelected: Boolean Action Action: the task to be performed when the component is activated by a mouse movement or key press.
This should point to a user-defined procedure or function or an item on an action list. Align Align: Is used to align a Control component to a border of a parent control. Anchors Anchors: keep the edges of a control component a defined distance from certain borders of the parent control. property AutoSelect: Boolean Constraints Constraints: Sets the minimum and maximum sizes for a control.
If a control is resized the new dimensions are always within the ranges given here.
You should take care when setting these options that they do not conflict with the Anchors and Align settings. Char Case Character Case: the default character case (Upper or Lower case) to be used in the Edit Box. Can, of course, be over-ridden by use of the [shift] key. Enabled Enabled: flag to determine whether or not the control is able to be used On Change - Action On Change - Action to be taken when any of the properties of the control change (especially the textual content).
User-defined Procedure On Change Bounds - Action On Change Bounds - Action to be taken if any of the bounds of the control are changed.
User-defined Procedure. On Click - Action On Click - Action to be taken when the mouse button is clicked with the cursor over this control. User-defined Procedure On Entry - Action On Entry - Action to be taken when the mouse cursor or text cursor enters the bounds of this control. User-defined Procedure On Exit - Action On Exit - Action to be taken when the mouse or text cursor leaves this control or when focus is relinquished. User-defined Procedure On Key Down - Action On Key Down - Action to be taken if a key is down while focus is in this control. Subtly different from On Key Pressed - for example the key might already have been down when focus entered this control, whereas On Key Pressed requires the key to become pressed while focus is in the control.
User-defined Procedure On Key Press - Action On Key Press - Action to be taken if a key becomes pressed while focus is in this control. Subtly different from On Key Down, which simply responds to a key being down, whether or not it was already down when focus was given to this control. On Key Press requires that a key becomes pressed while focus in in this control.
User-defined Procedure On Key Up - Action On Key Up - Action to be taken if a key is up (ie not pressed) while focus is in this control.
User-defined Procedure On Mouse Down - Action On Mouse Down - Action to be taken if the mouse button is down while focus is in this control.
User-defined Procedure On Mouse Move - Action On Mouse Move - Action to be taken if the mouse cursor moves while focus is in this control.
User-defined Procedure On Mouse Up - Action On Mouse Up - Action to be taken if the mouse button is up (not pressed) while focus is in this control.
User -defined Procedure On Resize - Action On Resize - Action to be taken when the control is resized. Might include re-alignment of text or selection of a different font size etc.
User-defined Procedure Password Character Password Character - defines which character should appear in the edit box when a password is being typed.
A security feature to prevent casual onlookers fom seeing the password that is being entered.
Most often an asterisk * but could be any user-selected character. Popup Menu Popup Menu - a menu that appears when the right mouse button is clicked over this control Read Only Read Only - a flag that signifies that users can view the contents of this control but are not allowed to modify it. Show Hint Show Hint - allows a small box containing helpful text to be displayed while the mouse cursor 'hovers' over the control Text Text - the actual character string that represents the contents of the control. May be edited if ReadOnly property is not set Visible Visible - determines whether or not the control can be seen Memo Box Memo box: for entry or display of multiple lines of text.
Inherits most of its properties from TCustomMemo Lines Lines: an array of strings (representing single lines of characters) which contains the textual material held or being entered in the Memo. Max Length Max Length: the maximum permitted length for the textual material in the memo Word Wrap Word Wrap: a logical flag to show whether or not word-wrap is enabled, ie if a word nears the end of a line and is going to be too long for the line, it is wrapped down to the next line Custom Label Custom label: the base type from which Label is derived. Label Label: a brief text label to be placed in the Form near any object that needs to be identified.
Can also be used for displaying text messages, eg
...
Label.Caption := 'Please select one of these options';
...
or the message may be changed dynamically, eg
var Lies: boolean;
...
if (Lies=true) then Label.caption := 'Lies are true'
else Label.caption := 'Lies are false';
... Align Align: Is used to align a Control component to a border of a parent control. Anchors Anchors: keep the edges of a control component a defined distance from certain borders of the parent control. Caption Caption - the text string that represents the contents of the label Constraints Constraints: Sets the minimum and maximum sizes for a control.
If a control is resized the new dimensions are always within the ranges given here.
You should take care when setting these options that they do not conflict with the Anchors and Align settings. On Change Bounds On Change Bounds - Action to be taken if any of the bounds of the control are changed.
User-defined Procedure. On Click On Click - Action to be taken when the mouse button is clicked with the cursor over this control. User-defined Procedure On Double-click On Double-click - Action to be taken when the mouse button is double-clicked with the cursor over this control.
User-defined Procedure On Mouse Down - Action On Mouse Down - Action to be taken if the mouse button is down while focus is in this control.
User-defined Procedure On Mouse Entry On Mouse Entry - Action to be taken when the mouse cursor enters the bounds of this control. User-defined Procedure On Mouse Leaving On Mouse Leaving - Action to be taken when the mouse cursor leaves the boundaries of this control. User-defined Procedure. On Mouse Movement - Action On Mouse Movement - Action to be taken if the mouse cursor moves while within the bounds of this control. User-defined Procedure On Mouse Up On Mouse Up - Action to be taken if the mouse button is up while the cursor is over this control.
Implies that the mouse button was previously down and has been released. The case where the cursor enters the control but the mouse button has not yet been pressed is covered by OnMouseEnter.
User-defined Procedure On Resize - Action On Resize - Action to be taken when the control is resized. Might include re-alignment of text or selection of a different font size etc. User-defined Procedure Visible Visible - determines whether or not the control can be seen Word Wrap Word Wrap: a logical flag to show whether or not word-wrap is enabled, ie if a word is near the end of a line and is going to be too long for the line, it is wrapped down to the next line Button Control Button Control: Base Type for the Button (including Radio Button) and Check Box types ;
processes the detection of clicks and changes, and the checked/unchecked state of the component.
A rectangular button, whose shape can be specified, and which usually has an informative caption.
It is designed to be pressed or selected by the mouse cursor, and usually initiates some activity with the OnClick Event.
Properties can include [Checked], [Click] (mouse clicks on button) and the actions to be taken on a change in a property.
Typically, clicking on the box will cause the box to be checked (or unchecked if it is already checked) as well as initiating any other action associated with the box.
The programmer is responsible for ensuring that the appropriate actions and changes in checked status are performed. TButtonControl constructor TCustomButton - the ancestor class for TButton TCustomButton is the ancestor for TButton
This class defines several of the methods to be used by descendant classes such as TButton
Use this class if you want to derive your own Button Class Creates a new instance of the TCustomButton class If you drop a component on the form editor you don´t need to add code to explicitly create it. The component is automatically created together with the the form, and destroyed when the form is destroyed.
However, if you create the component by code don´t forget to free it when it is no longer needed.

Constructors allocate memory and system resources needed by the object. They also call the constructor of any sub-objects present in the class. Performs the action associated with the button if it is the Default button Performs the action associated with the button if it is a Cancel button or if 'Escape' was pressed What Colour is the button? (default is the same as all other button faces) Is this the Default button? (default setting is False) Is a Modal Result awaited? (default is false) Is this the Cancel button? (default setting is False) Is the Button included in the TabStop list? (default setting is True) The most basic button component Button: Base type for all Buttons. A push button control. The user pushes a button (eg selects it with the mouse cursor and clicks the mouse) to start an action. Click, calling this method will invoke the OnClick event of the button If you want to programmatically Click on a button you can call its Click method. This will have the same effect as a user clicking on the button. The action executed when the user clicks the button. If you assign an action from an ActionList to a TButton.Action the corresponding execute-method is assigned to the OnClick event of the button.
Assigning an action sets other properties of the button as well, like Enabled and Caption.

Possible values fo Align are:
alTop: Places the control at the top, using the full clientwidth of its parent control.
alBottom: Places the control at the bottom, using the full clientwidth of its parent control.
alLeft: Places the control at the left side of its parent and uses the available height between any top or bottom alligned controls.
alRight: Like alLeft but on the right side of the parent control.
alNone: The control can be placed anywhere on the parent control.
alClient: The control takes all available space on parent control next to controls aligned to the top, bottom, right or left. Anchors are used to keep a button on a defined distance to certain borders of the parent control. Anchors can be used to keep control at a certain distance from a side of its parent control, when the parent control is resized.
For instance setting Anchors to [akBottom, akRight] will keep the control at a constant distance to the bottom right corner. Autosize in TButton has no function. If this property is set to true, the control will automatically adapt its size to be able to accomodate its content.
This property is not used in Buttons. The fixed spacing around the border of the Button Setting this property will make the OnClick event executed when the user hits ESC. Setting this property to true, will have the effect that when the user hits ESC this button is Clicked. Usually the Button which reacts to ESC sets the ModalResult of the form to mrCancel. Sets the text displayed on the button. Constraints can be used to give a control certain minimum and or maximum dimensions. Sets the minimum and maximum sizes for a control. If a control is resized the new dimensions are allways within the ranges given here. You should take care when setting these options that they do not conflict with the Anchors en Allign settings. Setting this property will make the OnClick event executed when the user hits ENTER Defines if a button is the default on a form. That is, pressing enter will execute its onClick wether the control has focus or not! Determines if the button reacts to a click. Setting this property determines if the control can be used.
If Enabled is false a button cannot be clicked. Setting the Enabled property to false also makes its appearance grayed.
If an Action has been assigned to the button and this action is disabled then the enabled property is set to false as well. Font is used to set the font of the caption of the Button. Font is used to set the font of the caption of the Button. If the button gets clicked, the ModalResult of the form will be set to this value. Setting ModalResult of a button makes closing a form easy.
Just set this property to a value different from mrNone and a click on this button will set the modalresult of the form it is placed on to this value.
Setting the ModalResult of a form will make it close. The OnClick event is triggered when a user clicks on the button The OnClick event is triggered when a user clicks on the button. It can also be invoked by calling the Click method. The OnEnter event is triggered when the button gets focus. The OnEnter event is triggered when the button gets focus. The OnExit event is triggered when the button loses focus. The OnExit event is triggered when the button loses focus. TabOrder - an integer value to show where the button lies in the Tab Order for this Form Boolean to determine whether the Button is associated with a Tab Stop in the Tab Order for the form Determines whether the Button is visible. Check Box State Check Box State: a set of constants defining the possible states of a Check Box -
Checked, meaning it has been selected;
Unchecked meaning irt has not been selected or has been deselected;
Grayed meaning it has been rendered inoperative or unable to be selected and appears grey or faintly visible on the Form The check box has no check mark, indicating that the user has not selected the option. The check box has a check mark in it, indicating that the user has selected the option. The check box has a check mark in it, but it is grayed. TCustomCheckBox is the ancestor of all check-box components. Custom Check Box: The base (abstract) class from which the TCheckBox is derived. Check boxes present the user with options that can be selected (checked) or deselected (unchecked). Determines whether the check box can be in a "grayed" state. If AllowGrayed is set to True, the check box has three possible states: checked, unchecked and grayed. If AllowGrayed is set to False, the check box has only two possible states: checked and unchecked. Indicates whether the check box is selected, deselected or grayed. See TCheckBoxState for possible values of State. Determines if the user can tab to a control. Use the TabStop to allow or disallow access to the control using the Tab key. If the TabStop is True, the control is in the tab order. If TabStop is False, the control is not in the tab order and the user can't press the Tab key to move to the control. Check Box Check Box: a small box which can contain a check mark to indicate that it has been selected by a mouse click. May be associated with a Caption that describes its function.
Toggles between being checked and unchecked on successive clicks of the mouse, and usually initiates some action associated with OnChecked. Action Action: the task to be performed when the component is activated by a mouse movement or key press.
This should point to a user-defined procedure or function or an item on an action list. Align Align: Is used to align a Control component to a border of a parent control. Allow Grayed Allow Grayed: a flag to show whether the box is allowed to be Greyed out,
ie it is still visible, but appears faint and cannot be selected or activated with the mouse cursor or keyboard Anchors Anchors: keep the edges of a control component a defined distance from certain borders of the parent control. Caption Caption: a brief description appearing near the check box, usually stating the function of the box or what action will be taken if it becomes checked. Checked Checked - shows whether or not the box has been checked (ie selected) Constraints Constraints: Sets the minimum and maximum sizes for a control.
If a control is resized the new dimensions are always within the ranges given here.
You should take care when setting these options that they do not conflict with the Anchors and Align settings. Enabled Enabled: flag to determine whether or not the control is able to be used Hint Hint: a short piece of pop-up text that appears if the mouse-cursor hovers over the check box;
it should give further details of the function of the box On Change On Change - Action to be taken when any of the properties of the control change.
User-defined Procedure On Change Bounds On Change Bounds - Action to be taken if any of the bounds of the control are changed.
User-defined Procedure. On Click - Action On Click - Action to be taken when the mouse button is clicked with the cursor over this control.
User-defined Procedure On Entry - Action On Entry - Action to be taken when the mouse cursor or text cursor enters the bounds of this control. User-defined Procedure On Exit - Action to be taken when the mouse or text cursor leaves this control or when focus is relinquished.
User-defined Procedure On Mouse Down - Action On Mouse Down - Action to be taken if the mouse button is down while focus is in this control.
User-defined Procedure On Mouse Move - Action On Mouse Move - Action to be taken if the mouse cursor moves while focus is in this control.
User-defined Procedure On Mouse Up - Action On Mouse Up - Action to be taken if the mouse button is up (not pressed) while focus is in this control.
User -defined Procedure On Resize - Action On Resize - Action to be taken when the control is resized. Might include selection of a different font size etc.
User-defined Procedure Popup Menu Popup Menu - a menu that appears when the right mouse button is clicked over this control Show Hint Show Hint: a flag to show whether or not the hint is to be shown when the mouse cursor hovers over the box. Visible Visible - determines whether or not the control can be seen Toggle Box Toggle Box: a labelled box capable of being checked (when it becomes recessed) or unchecked (when it is raised).
The 'state' property can be tested for cbUnchecked or cbChecked and actions can be associated with mouse clicks or other movements Radio Button Radio Button: a button which works in conjunction with other Radio Buttons in a mutually exclusive manner - if one button of a group is selected, none of the others in that group can be selected.
Several radio buttons are usually grouped together in a Group Box or Radio Group. When a button is selected, the actions associated with that button are initiated. Custom Static Text Custom Static Text: the base type from which Static Text is derived. FAutoSelected: Boolean Private variable for property AutoSelected. True indicate that the edit or combobox control has just performed an AutoSelect operation so that subsequent mouse-clicks and keystrokes proceeds normally without selecting the text. False is set when the edit or combobox control looses focus. Static Text Static Text: a box to display a Constant Text String Align Align: Is used to align a Static Text box to a border of a parent control. Anchors Anchors: keep the edges of a static text box a defined distance from certain borders of the parent control. Caption Caption: the text that actually appears with the Static Text Box Constraints Constraints: Sets the minimum and maximum sizes for a control.
If a control is resized the new dimensions are always within the ranges given here.
You should take care when setting these options that they do not conflict with the Anchors and Align settings. Enabled Enabled: flag to determine whether or not the control is able to be used Popup Menu Popup Menu - a menu that appears when the right mouse button is clicked over this control Show Hint Show Hint - allows a small box containing helpful text to be displayed while the mouse cursor 'hovers' over the control Visible Visible - determines whether or not the control can be seen On Click - Action On Click - Action to be taken when the mouse button is clicked with the cursor over this control. User-defined Procedure On Double-click - Action On Double-click - Action to be taken when the mouse button is double-clicked while the cursor is over the control. User-defined Procedure On Mouse Down - Action On Mouse Down - Action to be taken when the mouse button is down while the cursor is over this control. User-defined Procedure On Mouse Movement - Action On Mouse Movement - Action to be taken if the mouse cursor moves within the bounds of this control. User-defined Procedure On Mouse Up - Action On Mouse Up - Action to be taken if the mouse button is up while the cursor is over this control.
Implies that the mouse button was previously down and has been released. The case where the cursor enters the control but the mouse button has not yet been pressed is covered by OnMouseEnter.
User-defined Procedure On Mouse Entry - Action On Mouse Entry - Action to be taken when the mouse cursor enters the bounds of this control. User-defined Procedure On Mouse Leaving - Action On Mouse Leaving - Action to be taken when the mouse cursor leaves the boundaries of this control. User-defined Procedure. On Resize - Action On Resize - Action to be taken when the control is resized. Might include re-alignment of text or selection of a different font size etc. User-defined Procedure How to use StdCtrls

The Unit StdCtrls contains definitions and descriptions of many of the most commonly used controls for constructing Forms and other Objects in Lazarus Applications.

Many of the final target controls that the application developer wants to use, such as TButton, TMemo, TScrollBar etc, have a corresponding ancestor class such as TCustomButton, TCustomMemo or TCustomScrollBar. Many of the properties and methods relevant to the final target control are defined fully in the TCustomXXX class, and are inherited by the final target control.

If you drop a component on the form editor you don´t need to add code to explicitly create it. The component is automatically created by the IDE together with the form, and destroyed when the form is destroyed.

However, if you create the component yourself by code don´t forget to free it when it is no longer needed.


Constructors allocate memory and system resources needed by the object. They also call the constructor of any sub-objects present in the class.

Destructors: If you call Destroy for an object which hasn´t being initialized yet it will generate an error. Always use the Free method to deallocate objects, because it verifies if an object variable doesn´t contain the value nil.

Take the following precautions when creating your own Destroy method:

* Declare Destroy with the override directive, because it is a virtual method.

* Always call 'inherited Destroy;' as the last thing on the destructor code.

* An exception may be raised on the constructor in case there is not enought memory to create an object, or something else goes wrong. If the exception is not handled inside the constructor, the object will be only partially built. In this case Destroy will be called, so your destructor must check if the resources were really allocated before disposing of them.

* Remember to call Free for all objects created on the constructor.