Hi, can you upload a GIF or a video that shows exactly what is happening?

Also, did you install youtube-dl-gui using the setup file or did you build it from source?

Here's the video:
https://www.useloom.com/share/d0d8f3657643456ba26eb0e255bcdf45

I did not build from the source. I installed using the "windows installer'.

I have no idea why this is happening and i can't reproduce it on my side.

I use wx.PopupTransientWindow to implement the formats dropdown.
From the wxPython docs on the wx.PopupTransientWindow:

disappears automatically when the user clicks mouse outside it or if it loses focus in any other way.

I guess something on your PC cause the window to lose focus...

Also, what is the window that appears exactly under the youtube-dlg's "Welcome" message?
It seems to appear everytime you open the formats dropdown.

Update

popuptest.py.txt

If you know how to run python code using the command line (cmd.exe) you can try to run the attached python script. When the "Test" window appears you can click the "Test Popup" button, which will show the popup window (with orange color) with a button inside it. If the orange popup window goes away when you hover your mouse over it, this means that the problem is with your system wxPython else if the orange popup window stays and you are able to press the button inside it, then the problem is on our side.

In order to run the script you need python 2.7.* & wxPython 3.

@ajitgoel
Did you try the attached script?

https://github.com/MrS0m30n3/youtube-dl-gui/files/1564942/popuptest.py.txt