Sometimes taskbar icon jitters and instacloses.

[Martenfur]

This happens every time every first launch. On icon right click, the context menu appears in the wrong place and instantly disappears.

[Martenfur]

Seems to have something to do with window not being focusable. Not sure how to fix it.

[alfish2000]

I've spent some time on the topic yesterday.
But I could not find a solution till now.
I've found some equal behaviors with message boxes insta-closing when there is no main UI thread.
After insta-closing, the next message boxes are working:
https://stackoverflow.com/questions/28017576/wpf-taskbaricon-contextmenu

I can reproduce it also with:

1. left-click tray icon (main window is hidden)
2. left-click tray icon again (main window is shown again)
3. right-click tray icon (the context menu is shown shortly and insta-closes again)
4. right-click tray icon again (the context menu is shown and stays)
   goto 1.

It "feels" like it could be related.

And you are right, if the "WS_EX_NOACTIVATE" part is disabled, the problem is gone.
But then the main window is stealing the focus.