Instead of sending wxEVT_COLOURPICKER_CHANGED event from the button
itself and then catching it in wxColourPickerCtrl and resending an event
from the control from there, just send the event originating from the
correct object directly.
This allows to slightly simplify the code and will be especially useful
for other events, to be added in the upcoming commits, to avoid having
to write the same forwarding code for all of them.
5b7114b4d7