@trounces
I had a similar problem. My thread started here and was moved to its own by admin. Similarly, when resizing (or sometimes loading) a KeePassX window the whole screen would lock up but background things (like audio) would still work.
Oddly, replacing KeePassX with KeePass2 “solved” the problem. The best I can figure is… in my case at least, looking in the Xen logs, I see IOMMU warnings about the graphics driver. The best I can figure is it’s one of two things: (1) Poor IOMMU driver compatibility that’s agitated by certain applications doing certain things visually (2) Some poor graphics interop between VM space and the Xen final composite master display that is agitated by how some applications do certain things graphically.
I am able to replicate my test case reliably on two different laptops (one running Ryzen 5 PRO and another running Ryzen 7 PRO). The 7 model seems to tolerate a bit more of the KeePassX windows open but can be agitated to freeze with minimal effort.