slow eyedropper/alt key bug

I've been having this problem for a while: 

when pressing alt, the eyedropper doesn't trigger and the color doesn't get picked.

I thought there was a problem with my keyboard and tested it with another with the same results.

if you have say a brush selected and try to quickly, repeatedly pressing the alt key with the left alt you'll see that the eyedropper icon appears only half of the time so its quite slow triggering it,

whereas if I use the altgr button its very responsive as you would expect.

can anyone reproduce or provide any workaround? its very annoying when painting on it.

thanks!