please consider placing a small "X" close button on the right side of every tabbed contact sheet. it would mean the width of the tabs would grow wider to accommodate the close button.
an example of this is Mozilla Firefox and Opera web browsers.
Portable Application's version of Notepad++ Portable has in it's options menu, the choice to put the "X" close button on every tab or just one "X" close button like the way it is now in PhotoMechanic 4.5.3 Windows.
the thought behind this request is that it means moving the mouse around a little bit less and to try to get things done on deadline faster with less hunting around for buttons.