To distinguish it more quickly from mirror(clone) item and rotation items. Also show it only if icons in menus are turned on

Add menuitem for mirroring same output to all displays

Toggle between mirrored mode and xinerama mode (displays all on, laid out left to right)

When enabling org.mate.interface window-scaling-factor-qt-sync (default), m-s-d will attempt to set QT_SCALE_FACTOR during the init phase.
When disabled, the user can then choose to control this env var elsewhere.

Rotations can't be appled to a turned-off monitor. Also follow the display capplet color theme for monitors that have been turned off in the default monitor label background color

Add menu item to allow turning a monitor on or off from the popup menu. Borrow code from m-s-d display capplet to set geometry when a monitor is turned on. Turning on a monitor now works the same was as when turning it on but not reconfiguring it in mate-control-center's display capplet

Also ensure default bg images don't override label bg color, and don't use symbolic icon in GNOME HighContrast themes as it gets the disabled color