[Improvement] Keep toolbar open when tab-switching as long as Ctrl is being held

[Nillinn]

Briefly make the toolbar popup when switching or opening new tabs in compact mode

Currently, with this setting enabled, when pressing Zen's default keybind for switching tabs ( Ctrl+Tab ), the toolbar appears only for a brief second. To keep seeing the toolbar, the user must keep switching tabs in an interval of less than a second ( 'mashing' the Tab key ) .

I'd like to suggest a change, to mantain the toolbar open as long as the user remains holding the Ctrl key, allowing them to see the tab list and have a better time navigating through tabs.

This change would be very useful for users keeping their toolbar hidden.