onFocus
fun SwingModifier.onFocus(onGained: () -> Unit = UNDECLARED_ACTION, onLost: () -> Unit = UNDECLARED_ACTION): SwingModifier
Installs focus gained/lost handlers.
A callback left undeclared reports nowhere, and declaring neither is refused.
Return
this chain with the focus handlers declared on it.
Parameters
onGained
runs when the component becomes the focus owner, its window regaining activation included.
onLost
runs when it stops being the focus owner, the temporary loss while another window is active included.