From fd45a904f46083d603ee73295f774309edf1210e Mon Sep 17 00:00:00 2001
From: paul <paul@lazarus-ide.org>
Date: Sat, 7 Apr 2007 16:45:10 +0000
Subject: [PATCH] - fixing AV during Drag and Drop operation - looking on non
 TWinControl objects while drop (0008628)

git-svn-id: trunk@10914 -
---
 lcl/include/dragdock.inc   |  8 +++++---
 lcl/include/dragobject.inc | 17 ++++++++++++++++-
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/lcl/include/dragdock.inc b/lcl/include/dragdock.inc
index 6d19d70be2..f0f30a7653 100644
--- a/lcl/include/dragdock.inc
+++ b/lcl/include/dragdock.inc
@@ -245,10 +245,12 @@ Begin
   {$IFDEF VerboseDrag}
   DebugLn('DragTo P=',Position.X,',',Position.Y);
   {$ENDIF}
-  if (ActiveDrag = dopNone)
-  and (Abs(DragStartPos.X - Position.X) < DragThreshold)
-  and (Abs(DragStartPos.Y - Position.Y) < DragThreshold) then begin
+  if (DragControl = nil) or ((ActiveDrag = dopNone) and
+     (Abs(DragStartPos.X - Position.X) < DragThreshold) and
+     (Abs(DragStartPos.Y - Position.Y) < DragThreshold)) then
+  begin
     // dragging not yet started
+    // or CancelDrag happened (DragControl = nil)
     exit;
   end;
 
diff --git a/lcl/include/dragobject.inc b/lcl/include/dragobject.inc
index 0a9d72a3f3..790be835d8 100644
--- a/lcl/include/dragobject.inc
+++ b/lcl/include/dragobject.inc
@@ -72,8 +72,23 @@ begin
 end;
 
 procedure TDragObject.CaptureChanged(OldCaptureControl: TControl);
+var
+  i: integer;
+  IsDragging: Boolean;
 begin
-  DragDone(OldCaptureControl.Dragging);
+  // if this is TWinControl, and it have controls (not TWinControls)
+  // then we should check Dragging in those controls
+  IsDragging := OldCaptureControl.Dragging;
+  if (not IsDragging) and (OldCaptureControl is TWinControl) then
+  begin
+    for i := 0 to TWinControl(OldCaptureControl).ControlCount - 1 do
+    begin
+      IsDragging := IsDragging or TWinControl(OldCaptureControl).Controls[i].Dragging;
+      if IsDragging then
+        break;
+    end;
+  end;
+  DragDone(IsDragging);
 end;
 
 procedure TDragObject.KeyDown(var Key: Word; Shift: TShiftState);