Regression: missing screen updates in 4.1.6 (both SDL and RDP)

[Markus Duft]

Hi!

Since upgrading vbox to 4.1.6 (and installing according guest additions), my windows xp is no longer fun to work with. it behaves as if a whole lot of screen updates are dropped. for example when doing powerpoint presentations in the vm, the mouse disappears when typing (as it should), but only re-appears when i click (as opposed to when i move it, as it should). Also highlighting a word in office brings up that quick toolbar. it does appear at first very transparently, but it doesn't get "solid" as it should when i move the mouse over it.

also for example i was unable to move an icon on the desktop, etc.