Currenty daily snapshots seem to have a broken mouse click behaviour in X.org
when running inside Virtualbox. Not yet sure whether it's a bug in the
virtualbox driver or in X.org or .... - needs investigation.

Related:
http://git.debian.org/?p=pkg-xorg/debian/xorg.git;a=blob_plain;f=debian/xserver-xorg.NEWS;hb=4d0132f3a02edac5e64dd84402a450a9052e1da2