I have found it! Silly me. I have placed view.invalidate at the end of draw method 😳
def draw(view)
if( @ip1.valid? )
if( @ip1.display? )
@ip1.draw(view)
@drawn = true
end
end
if( @ip2.valid? )
@ip2.draw(view) if( @ip2.display?)
self.draw_geometry(@ip1.position, @ip2.position, view)
view.invalidate #WRONG!
@drawn = true
end
end
Each time UI.messagebox was invoked SU called draw method which erased MB from the view.
Thanks
Tomasz