'New Activity Flashes Taskbar' causes taskbar to ignore repaint on Windows 8

Whenever the Windows taskbar button would flash, it instead is highlighted in yellow, and the entire taskbar no longer responds to repaint events.

Repro Steps:
1. Launch MUSHClient 4.84
2. Open any world with 'New Activity Flashes Taskbar' enabled
3. Give any other application focus
4. Wait for activity on the opened world.

Expected Behavior:
Windows Taskbar button for MUSHClient flashes to alert the user.

Actual Behavior:
Windows Taskbar button for MUSHClient is highlighted, but does not flash. The entire taskbar no longer repaints. The clock stops. Buttons on the taskbar can be clicked, but there is no 'click' animation from the taskbar button itself (maximize animations do occur). If the taskbar buttons move for any reason (such as an application being closed), the taskbar does not reflect this change, causing the user to mis-click taskbar buttons (the taskbar still responds to clicks, but since the buttons have been moved around, the x/y coordinate of the click is hitting something the user can't see).

Workarounds:
Disable 'New Activity Flashes Taskbar' option.
Open any fullscreen app on the primary monitor (the easiest way to do this is to tap the 'Start' button, which brings up the new Modern UI-based Start Menu, then 'Start' again to immediately dismiss it).

Additional Information:
MUSHClient version: 4.84
OS Version: Windows 8 Enterprise
Graphics Card: NVIDIA GeForce 9800 GTX

Thanks for the bug report, however I have no plans at present to buy Windows 8, nor an updated compiler that would support it.

Since the code is freely available on GitHub, if any other developer can suggest a change that would fix this, I could incorporate that into future versions.

I notice that calls to FlashWindowEx are commented out in mainfrm.cpp. Maybe it would work better than FlashWindow? I have to say that it doesn't look like there's a whole lot that can be done here. A system API call either works or it doesn't. :\

This reported non-repainting behavior sounds like an OS bug.

I think FlashWindow is a deprecated call, but I would have commented out FlashWindowEx for a reason. It fixed one thing, but caused another problem?

No idea. It just says something about winver.