Steps to reproduce.
- Open multiple chrome windows with the UIO+ extension installed
- hold down the ctrl key and scroll with the mouse to zoom
- Notice that the magnification locks up as it tries to switch between multiple values.
This only seems to happen in Windows and only when there are multiple Chrome windows (not tabs) open. If you use the ctrl+(+/-) keys it works because it waits for the window to have focus before trying to change the zoom level.