Window flashing case 1
When I open a dialog from application A Ion starts quickly switching between this dialog and the main window.
The application is flawed and tries to manage its dialog windows instead of letting the window manager do its job: the dialog doesn't have the transient_for hint set and when Ion displays this window, it unmaps (hides) the main window. The broken application now thinks that the user wants to hide the whole application instead of just the main window and therefore unmaps the dialog. But as the dialog is unmapped Ion switches back to the main window and now the application wants to show the dialog too. We have a loop.
See the configuration manual for details setting up the “acrobatic” winprop to fix this.
See also: Window flashing case 2.