I have a similar issue on Linux but symptoms are a little different:
SlickEdit version: SlickEdit Pro 2019 (v24.0.0.8 64-bit)
OS: Linux
OS Version: Ubuntu 19.10
Kernel Level: 5.3.0-64-generic
Build Version: #58-Ubuntu SMP Fri Jul 10 19:33:51 UTC 2020
Processor Architecture: x86_64
If I type in e.g. 'vs foo.txt' to edit a new file or bring an existing file into focus, then it gets loaded as expected in SlickEdit, but SlickEdit does not come into focus, and the terminal is also no longer in focus. Not sure where the focus is. Then if I type alt-tab to switch to SlickEdit then it still doesn't come into focus. Only when I alt-tab a second time then will it finally comes into focus. Instead of 2x alt-tab then I can mouse click on only the top menu bar of SlickEdit to change focus with the mouse, but clicking on any other part of the SlickEdit windows seems to ignore the mouse.
After focus is finally switched to SlickEdit then I can alt-tab backwards and forwards between it and any other GUI window without issue, etc. Or I can mouse click on any other GUI window and then mouse click on any part of the SlickEdit window to get focus back. So the focus issue only seems to happen directly after typing 'vs <file>'...
Note: If I type 'vs +new <file>' or 'vs +new <file> &' then I'll get a new SlickEdit window in focus immediately, and no need to hit alt-tab, etc.
Note: All other GUI apps behave just fine with either alt-tab or the mouse clicking anywere on the window. Also, I have no SlickEdit windows 'undocked' etc; just one big window. I noticed this seems to have been an issue with SlickEdit as far back as 2007 [1] ? And again in 2009 [2] and 2010 [3].
Any ideas how to make SlickEdit behave better?
[1]
https://community.slickedit.com/index.php/topic,2487.msg10324.html#msg10324[2]
https://community.slickedit.com/index.php/topic,4738.msg19813.html#msg19813[3]
https://community.slickedit.com/index.php/topic,6041.msg24951.html#msg24951