lcl: apply few comments related to docking from Hans-Peter Diettrich (issue #0013118)

git-svn-id: trunk@18625 -

lcl/controls.pp

@@ -451,6 +451,10 @@ type
   { TDockManager is an abstract class for managing a dock site's docked
     controls. See TDockTree below for the more info.
     }
+{ TODO -cdocking : More (flexible) event handlers are required, for:
+- all docking related messages, based on a TDragDockObject parameter
+- changed visibility of docked controls (and more?)
+ }
   TDockManager = class(TPersistent)
   public
     procedure BeginUpdate; virtual; abstract;
@@ -3440,6 +3444,8 @@ end;
 
 constructor TDragManager.Create(TheOwner: TComponent);
 begin
+{ TODO -cdocking : DragImmediate should apply to drag-drop only, while drag-dock never should start immediately
+ }
   inherited Create(TheOwner);
   FDragImmediate := True;
   FDragThreshold := 5;

lcl/include/control.inc

@@ -59,7 +59,7 @@ end;
   Returns: Nothing
 
   Starts the dragging of a control. If the Immediate flag is set, dragging
-  starts immediately.
+  starts immediately. A drag-dock should not normally start immediately!
  ------------------------------------------------------------------------------}
 procedure TControl.BeginDrag(Immediate: Boolean; Threshold: Integer);
 begin
@@ -71,6 +71,11 @@ end;
 ------------------------------------------------------------------------------}
 procedure TControl.BeginAutoDrag;
 begin
+{ TODO -cdocking : Automatic drag-dock never should start immediately.
+A docked control should not try to undock itself, at least not immediately.
+A docked control also should stay docked until it is really dropped into a different location,
+so that a docking mangager can detect and handle (abort) an drop into the old place.
+ }
   BeginDrag(DragManager.DragImmediate, DragManager.DragThreshold);
 end;
 
@@ -1313,6 +1318,8 @@ end;
 
 procedure TControl.VisibleChanged;
 begin
+{ TODO -cdocking : For docked controls, the docking manager must receive a notification!
+ }
   DoCallNotifyHandler(chtOnVisibleChanged);
 end;
 
@@ -3540,6 +3547,8 @@ begin
       // undock from old HostSite
       // - this only undocks from the DockManager
       // - this control still uses the DockSite as parent control
+      { TODO -cdocking : Combine with ManualFloat, for consistent handling
+ }
       DebugLn('TControl.ManualDock UNDOCKING ',Name);
       Result:=HostDockSite.DoUndock(NewDockSite,Self);
     end;

lcl/include/wincontrol.inc

@@ -3453,6 +3453,19 @@ function TWinControl.DoDragMsg(ADragMessage: TDragMessage; APosition: TPoint; AD
 var
   TargetControl: TControl;
 begin
+{ TODO -cdocking : All docking related messages should be handled here!
+The base class (TControl) cannot be involved in docking, lacking an docking manager.
+
+The messages could be sent immediately to the docking manager, if this is a dock site.
+ }
+{ if ADocking and UseDockManger then //...we always have an DockManger!
+    DockManger.Dock/DragMsg(...)
+//or:
+    case ADragMessage of
+    ...
+    end
+  else //drag-drop
+}
   case ADragMessage of
     dmFindTarget:
       begin
@@ -4856,6 +4869,12 @@ begin
     if not Result then
       Exit;
   end;
+{ TODO -cdocking : Also ask docking manager!
+In case of a drop into the old location the undock operation should be aborted,
+because then the docking manager (DragDockObject) would refer to an invalid (no more
+existing) target.
+ }
+
   if not KeepDockSiteSize then begin
     NewBounds:=BoundsRect;
     case Client.Align of