system.gui/system.nav functions should accept a Component object
When using custom functions or extension functions, there is no `event` object, only `self`.
This makes it very difficult to use the functions in system.gui/system.nav, as they all expect a `java.util.Event` object. I have looked into this and it seems that they only use the Event object to get a reference to the source component.
These functions should be changed to accept a `java.awt.Component` as well. This would allow us to use these functions within custom/extension functions, e.g. `system.gui.getParentWindow(self)`.