diff --git a/lcl/include/customcombobox.inc b/lcl/include/customcombobox.inc
index 7f5614e756..670d719e62 100644
--- a/lcl/include/customcombobox.inc
+++ b/lcl/include/customcombobox.inc
@@ -482,21 +482,24 @@ begin
 end;
 
 procedure TCustomComboBox.KeyUp(var Key: Word; Shift: TShiftState);
-var iSelStart: Integer;
-    sCompleteText, sPrefixText, sResultText: string;
+var
+  iSelStart: Integer; // byte position
+  sCompleteText, sPrefixText, sResultText: string;
 begin
  inherited KeyUp(Key, Shift);
  if ((cbactEnabled in FAutoCompleteText) and (Style <> csDropDownList)) then
   begin
    //Only happens with alpha-numeric keys and return key and editable Style
    if (IsEditableTextKey(Key) or (Key = VK_RETURN) or (ssShift in Shift)) then
-    begin
+   begin
      if (Key = VK_RETURN) then
-      SelectAll else
-      begin
+       SelectAll
+     else begin
        iSelStart := SelStart;//Capture original cursor position
        //End of line completion
-       if ((iSelStart < Length(Text)) and (cbactEndOfLineComplete in FAutoCompleteText)) then Exit;
+       if ((iSelStart < Length(Text))
+       and (cbactEndOfLineComplete in FAutoCompleteText)) then
+         Exit;
        sPrefixText := LeftStr(Text, iSelStart);
        sCompleteText := GetCompleteText(Text, iSelStart,
                                         (cbactSearchCaseSensitive in FAutoCompleteText),
diff --git a/lcl/stdctrls.pp b/lcl/stdctrls.pp
index ddbd888cc8..60662dcb07 100644
--- a/lcl/stdctrls.pp
+++ b/lcl/stdctrls.pp
@@ -378,8 +378,8 @@ type
     property Items: TStrings read FItems write SetItems;
     property ItemIndex: integer read GetItemIndex write SetItemIndex default -1;
     property ReadOnly: Boolean read FReadOnly write SetReadOnly stored IsReadOnlyStored;
-    property SelLength: integer read GetSelLength write SetSelLength;
-    property SelStart: integer read GetSelStart write SetSelStart;
+    property SelLength: integer read GetSelLength write SetSelLength;// byte length
+    property SelStart: integer read GetSelStart write SetSelStart;// byte position
     property SelText: String read GetSelText write SetSelText;
     property Style: TComboBoxStyle read FStyle write SetStyle;
     property Text;