From Kimmo Vuorinen:

Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html] I have few problems with GUI, when clicking video window in fullscreen mode to get mplayer controls to hide, video window goes black but movie continues to play. When I move mouse cursor to bottom of the screen and playbar appears video works again. Another problem is when closing mplayer from fullscreen mode video window position is saved and when starting mplayer again video window is on top left of the screen. Playbar also doesn't open when moving cursor quickly to bottom of the screen. I am using MPlayer cvs updated yesterday and xv video driver. These are minor problems but that would be great if someone could look into them.

I've this problem too , and is very annoying . Please , solve it , because I become mad any time I have to hide the MPlayer controls in 1.0pre versions . 0.92 doesn't have this problem , but that version doesn't seems to support Matroska container too. Please spend some time on this Thanks Marcello