[Chicken-users] strange IUP canvas behavior - mouse clicks returning bad value

[Matt Welland]

obj: #<tagged pointer Ihandle 17aa370>, pressed 0, status   1      
canvas-origin: 0 0 click at -1987635704 48

The -1987635704 is the x value returned by this callback:

#:button-cb (lambda (obj btn pressed x y status)
...

this is failing on Ubuntu 15.04 but working ok on sles11.

so far as I can tell this is not due to any changes in the code - running an older version exhibits the save behaviour.

Any suggestions on what to look at?

Thanks,

Matt
-=-