Sets the zoomed state for the active pane within this tab.
A zoomed pane takes up all available space in the tab, hiding all other panes while it is zoomed. Switching its zoom state off will restore the prior split arrangement.
Setting the zoom state to true zooms the pane if it wasn't already zoomed. Setting the zoom state to false un-zooms the pane if it was zoomed.
Returns the prior zoom state.