Mathworks explains this with the CTRL+Q event forwarded from the figure to the command window. This behavior seems to exist since R2014b. MatLab doesn’t seem to make a distinction between the modifiers (‘@’ is CTRL+ALT+Q). The official workaround is to populate the file menu either by clicking on it, or programmatically like this:

f = figure;
filemenufcn(f, 'FilePost');
uicontrol(f,'Style','edit')

Alternatively, the confirmation for closing should be activated. Once cancelling the confirmation, the ‘@’ symbol can be used without the effect.

IMHO, this is a critical bug for GUIs using edit fields for email addresses and the like, because data loss is very likely.

I’m wondering if the Figure class has some equivalent property for the behaviour of the mouse, i.e., a property that expresses if (in the moment of reading the property) the mouse is pressed, and which button.

When the window does not have focus then it should not handle any key-press event. It is the responsibility of the window that does have the focus to process it.

Actually, when figure has not the focus, java ‘KeyPressed’ event is not triggered. So, impossible to know when the clic is done which modifiers are pressed…

You can use the KeyPressedCallback property at the Java-frame level, then you don’t have any of these limitations.