Something strange started with these last changes:
Player in down-left corner, sticking to edges, default skin, not "Big", not in mini-mode;
Info window in top-left corner, sticking to edges, always opened in "Message" tab;
"Move with main window" NOT checked, "Auto-resize to fit contents" checked, "height limit: 500" (default?), "Text size: big", "Maximum text width: 108".
Now, if you switch to "Playlist / library" mode and then switch back to "Track info" mode, info window "falls down" and stick on top of player window, not returning to top-left corner where it was and should be.
Same happening also if you just switch to "Vis." tab and back to "Message" tab in "Track info" mode.
During all these manipulations info window obviously resized to different sizes.
Looks like info window somehow stopped remembering left-TOP corner position and now remembers only left-DOWN position, ignoring top.