Hey @Matsuiko (hirokamatsuiko),
Unfortunately this is an issue we are aware of. It is caused by the way we handle events received from the OS. If you keep a key pressed, after a short time, a new key press event is sent every few milliseconds. If we wanted to support this properly (or fix this glitch), we'd need to filter out those events which sounds easy and in fact is easy to code, but has to be done carefully as it may bring up a lot of new glitches. In the past we had similar report that have the same root, e.g. holding down R to rotate triggers a similar cursor glitch.

Some OSes have the option to turn these multiple press events off, like you can see here: http://i.imgur.com/vQSirqo.png Not sure how Windows handles this but you could try to google a bit ;)

So anyway, thanks for the report, but this is something known and expected.

PS, I recently worked with a newer developer to find a solution for this which seems to work out pretty well so far. So chances are this will be solved soon.