Distorted shape when dragging the columns

[Issamdnn]

When Dragging the columns it shows Distorted shape .

[joachimmarder]

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[Trevor-S]

This issue is occurring in the V8.0.3 release as well as the master repository code as at 2 October 2024 using Delphi 12.2.

The issue may be demonstrated using the "Minimal" or "Advanced (Tree in Grid Simulation)" demo applications by dragging the Tree column header with the mouse. The Drag image leaves artifacts during the dragging.

Additionally, when the DPI awareness is set to "DPI Unaware" on a Monitor with Scale greater than 100%, the drag image is positioned (offset) a far distance from the mouse. The further you move the mouse to the right or below the tree, the further away the drag image moves away from the mouse pointer.

HTH

[joachimmarder]

A very similar issue was discussed intensively in 2016 in issue #248.

[joachimmarder]

One possible solution could be implementing #806 and let Windows do the drawing.

[joachimmarder]

I have now implemented column header drag and drop using Windows drag and drop, and it looks promising so far. I would appreciate it if several people could do some testing.

[Trevor-S]

Thanks Joachim,
I have done basic testing using the Advance.exe demo and my own applications.

Delphi 12.2, Dual Monitor, 3840x2160 @125% and 1920x1080 @100%

In both DPI Monitor V2 and DPI Unaware the Draw image is operating correctly, keeping with the mouse cursor and scaled appropriately when moved between screens. No more drag drawing artifacts.

However, when the header is dragged over the Delphi 12.2 IDE edit window:
- the application hangs if debugging the application in the IDE,
- or an AV error is encountered if running the application outside the debugger.
In both cases, the application must be terminated using end task. This does NOT occur for me dragging over the Delphi 11.3 IDE edit window, nor does it occur in other applications I have tried dragging over including One Note, MS Word, VS code, Edge and Windows Explorer. Additionally, I haven't had an opportunity yet to investigate whether any of the IDE extensions could be the culprit.

I will continue using and testing.

[joachimmarder]

However, when the header is dragged over the Delphi 12.2 IDE edit window:

• the application hangs if debugging the application in the IDE,

I can confirm this. It is not a new behavior, it also occurs when using drag&drop with tree nodes. So it is a separate issue. I suppose it is a result of a bad drop target implementation in RAD Studio, especially since it does not occur with any other application. It shouldn't hurt too much in an average situation.