Thanks for your bug report. Yes, that is intentional. Colors throughout mIRC have now been standardized on a base set of light and dark mode Windows colors. The Treebar item color is now using the appropriate color for a non-focused treebar item. If you make the Treebar active by clicking in it, the selected item will turn blue. This was actually one of the benefits of working on dark mode - standardizing all of the colors across all features/functions/etc. This was quite tricky to do since Windows itself uses inconsistent colors across different win32 controls in light/dark modes. So more work was required with controls where Windows was actually using completely different colors to other list controls. I have settled on a set of light/dark mode colors that I think are reasonable overall.
