[Lazarus] Sparta Form Designer change

[Juha Manninen]

On Thu, Jul 27, 2017 at 1:24 AM, Anthony Walter via Lazarus
<lazarus at lists.lazarus-ide.org> wrote:
> Please see issue #32209 for a working fix. Someone familiar with the LCL Qt
> widget implementation needs to look at this in more depth.

The issue appears to be inherent to QT, not caused by LCL-QT code.
I added a comment in the bug tracker issue. I copy it here to reach more people:

I don't see any good reason for using PostMessage in Sparta form
designer code. It only makes the code more difficult to read and more
prone to widgetset specific problems, as we saw.
The messages
  WM_SETNOFRAME = WM_USER;
  WM_BoundToDesignTabSheet = WM_USER + 1;
and their handlers should be replaced with normal functions. Any
possible recursion can be avoided by boolean flags.
If the operation must be delayed, then OnIdle is the right way to go.
Or, is there something I don't understand?

Regards,
Juha