private T getTabbedValueBefore(T current) {
		if (current == null) {
			return allTabs.get(allTabs.size() - 1).getValue();
		}
		int tabIndex = getTabIndex(current);
		if (tabIndex >= 1) {
			return allTabs.get(tabIndex - 1).getValue();
		}
		if (hasHiddenTabs()) {
			return null;
		}
		return allTabs.get(allTabs.size() - 1).getValue();
	}
Returns the value of the tab that generated the given mouse event. If the mouse event
is not from one of the tabs, then null is returned.
@param event the MouseEvent to get a value for
@return the value of the tab that generated the mouse event
Ghidra/Framework/Docking/src/main/java/docking/widgets/tab/GTabPanel.java