events, mouse button 2

[Steven J Abner]

 I am transferring code that used gdk to xcb from a project I use to 
create objects not allowed by gdk/gtk plus the fact gdk3 cant work on 
gdk4 (common is letters gdk).
 Writing the event handler I came across an oddity and not sure how to 
guard against or make use of the feature? Mouse button 2 causes two 
different events to occur:
window 88080384, LEAVE_NOTIFY (537,93)
window 88080384, ENTER_NOTIFY (537,93)
window 88080384, BUTTON_PRESS Button 2 modifier 0 (537,93)
window 88080384, BUTTON_RELEASE Button 2 modifier 512 (537,93)
 Any ideas? I am a complete newbie to xcb so have pity on my ignorance.
Just in case window area, so point values mean something:
Window 88080384 EXPOSE. Region (0,0,800,200)
Please cc me 'cause not sure this is a one-shot so haven't joined list.
Steve