Full screen mode can allow mouse focus to other applications
Stellarium in full screen mode may hide from view regions which respond to mouse input.
- the windows taskbar, especially if in auto hide mode
- almost anything after an AC - battery switchover, power plan change, Alt-Tab
The effects of Alt-Tab depend on what is running and what the actual tab order is.
- application popup (e.g. task completed, taskbar notification bubble, virus warning)
The Alt-O bug in the ocular plugin (#80609) is an example of an invisible box able to receive mouse input, but created by Stellarium itself.
Usually such conditions are cleared by a mouse click outside the active region.
Many popup notifications have a timeout so the potential problem may disappear in a few seconds.
Those that persist often can cause an obvious problem only if some button is clicked by chance.
Often the only symptom is a single mouse click may seem to be ignored by stellarium.
Stay-on-top applications may be hidden by Stellarium but stay responsive to mouse input indefinitely
e.g. some calculator applications, drag and drop boxes.
The potential exists for a single mouse click in Stellarium to do virtually anything.
This has been observed for versions 0.11.2, 0.11.4 and 0.12.0beta2, all in both standard and no OpenGL2 modes, running Windows 7 Home Premium 64 bit on the following machines
Toshiba Qosmio F60
Nvidia GeForce GT 330M
Alienware M11x R3
Intel HD Graphics 3000
Nvidia GeForce GT 540M
Observed with Alienware M11x R3 running either GPU.
I have attached screenshots showing an example of what is visible to the user and what can receive mouse clicks.