event <-
buttons: mask=intBitmask containing various status information on the event. It is not
advised to rely on the contents of the bitmask as this might change in
the future.
The status of the modifier keys is normally tested using event->has_modifier.
The type of click (single, double, triple) is requested using
event<-multiclick
and the button for button-related events using event<-button.
Current definition of the mask-values
control-key 0x1
shift-key 0x2
meta-key 0x4
left-button 0x8
middle-button 0x10
right-button 0x20
single-click 0x40
double-click 0x80
triple-click 0xC0
