performTabClick
Clicks the tab at index on the matched JTabbedPane and settles the composition.
The click is a real MouseEvent aimed at the middle of that tab, so the pane's own UI decides what the click means, exactly as it does for a user: it maps the position back to a tab and selects it, which is what publishes the change to the pane's listeners and so to the callbacks a wrapper declares. Writing the pane's selected index instead is the composition's own kind of write rather than the user's, and a wrapper that tells those two apart cannot be tested that way.
Clicking does nothing where a user's click would also do nothing: on a tab of a disabled pane, or on a disabled tab. The strip stays where it was and the callbacks hear nothing.
Return
this interaction, for chaining a further gesture or assertion.
Parameters
the tab's index in the pane, which a strip laid out in several runs may not show in that order.
Throws
if the query does not resolve to a single node, if that node is not a JTabbedPane, if it has no tab at index, or if the strip does not currently show that tab - a click aimed at a tab with no position on the strip would land on nothing.