My experience is that it's Windows (or the Windows shell, at least) that has the problem, rather than Opus itself.
Windows sometimes gets confused about which toolbars are docked where, and you sometimes see it doing things like placing a gap between the toolbar and the edge of the screen, the same size as the toolbar (or something else which was docked there), because it thinks something else is still docked there when it isn't.
If you use multiple monitors with different DPIs then it gets even worse, and docking a toolbar to the side of one monitor can move things (e.g. the taskbar) around on the sides of others. Mixed DPI in windows is a mess. (To be fair, so few things support docked toolbars these days. Opus is the only thing I'm even aware of which still does. But there are other mixed-DPI bugs in Windows that are less forgivable.)
I have a system-wide hotkey (Alt + `) configured in Opus which toggles my docked toolbar on/off:
Toolbar NAME="Leo - Docked" STATE=float APPBAR=bottom TOGGLE
Any time it goes wrong I just double-tap that and it's fixed. That said, it hasn't gone wrong in a long time now, outside of testing mixed-DPI situations.