Called when normal tab activates (by click or code).
Called when "plus" pseudo-tab, or "plus" button (added in OptButtonLayout), clicked.
Called when user button clicked, which is char "0".."4" in OptButtonLayout.
Called when "x" mark clicked. You can override default tab deletion and show confirmation before closing a tab.
Called when "down arrow" clicked, which is "v" char in OptButtonLayout. You can disable default dropdown menu show.
Called before painting a tab or another element. You can disable default painting. Not called for user buttons.
Called after painting a tab or another element. This is called also for user buttons (chars "0".."4" in OptButtonLayout).
Called after control has no tabs anymore, after deleting last tab.
Called when mouse moves over control. Mouse-over tab index is passed to event.
Called after adding/deleting/moving tabs. Passed 2 indexes: NFrom, NTo. NFrom=-1 for adding, NTo=-1 for deleting, both >= 0 for moving.
Called before activating new tab. Can disable this activation.