Here's an interesting UI trick, as an example of what one can do with "filter" events:
Problem: I like right-click menus to add lots of options to graphs, but the Users seldom discover the right-click options. I would like an obvious menu button for the User to see, but have any click on the button open the graph menu.
Solution: put the button on the graph. On "Mouse Down?", hide the button and make the mouse click a right click. The Mouse Down then falls on the graph and triggers "Shortcut Menu Activation?", where I make the button visible again (the User never notices it being hidden).
Example Chart Menu Button.vi
LabVIEW 2015; controls from Flatline