Mouse Wheel Zoom doesn't always work when WaferMapPanel is added to an existing application

[Douglas Thor]

The discrete plot legend color boxes are actually buttons. When one of these values is changed, the mouse wheel (zoom) stops working.

[Douglas Thor]

Asked on StackOverflow:
http://stackoverflow.com/questions/27413232/wx-lib-evt-colourselect-interfering-with-wx-lib-floatcanvas-evt-mousewheel

[Douglas Thor]

This isn't limited to just the color_change operation.

It also breaks if the panel is in a custom app.