Reproduced with TC 9.50 beta 1 on Vista 32-bit:
0. Activate dark mode in TC.
1. Open text file with Lister avoiding plugins (Alt+Shift+F3).
1.1 Call Find text dialog:
it will be all dark, including OK, Cancel and Help buttons.
1.2 Search for a word that doesn't exist in a file, so you'll get Not found dialog:
It will also be all dark, including OK button.---------------------------
Not found:
---------------------------
text to find
---------------------------
ОК
---------------------------
2. Switch to plugin view (I used uliser).
2.1 Call Find text dialog: OK, Cancel and Help won't be dark-themed.
2.2 Search for text to get "Not found" dialog: it won't be dark-themed at all.
3. Return from plugin view to Lister's text view (mode 1).
3.1 Call Find text dialog: OK, Cancel and Help won't be dark-themed.
3.2 Search for text to get "Not found" dialog: OK button in it won't be dark-themed.
I'll update this post when will re-check it on Windows 10 too.
Edit: modified topic title to make it more correct. Original one was too general: "Dark Mode, Lister, Search dialog and plugins"