Canvas Error when scrolling off desktop

I am having a really bizarre problem. I am creating an app which interfaces to a series of spreadsheets and does a number of operations on them.

When you select a spread sheet from a list it creates a window and uses a canvas to create a custom list box.

Im almost finished and everything was going fine until i came across this weird bug

If you drag any of the windiows about until part of the canvas is off screen the canvas suddenly is moved out the window and onto the desktop (top left corner)

Its really bizare and ive no idea how to remedy it, any ideas?

Any chance of a short example on the problem?

Hmm, i went to put a small example of it together and it wasnt jumping off, so i tried my program again and it wasnt jumping off either.

I think ive determined it was a sideffect of remote desktop as when it was happening i was on remote desktop.

When i try using it through remote desktop now the canvases arent even being drawn (which was weird as they were yesterday).

So i think the weird behaviour must be a result of that.

But Thanks for replying anyway!, it was your request for an example that caused me to locate the problem : )