In Dynamics AX, the use of shortcut keys triggers a task. Some tasks do things, like Ctrl+F3 opening the advanced query window, while other tasks have been added just to allow override as needed, like many of the F keys (e.g. F4).
To override the standard behavior of a task, you can override the task method of that form e.g. \Forms\Form1\Methods\task.
Or for responding to that task across all forms, you can override the task method of the SysSetupFormRun class i.e. \Classes\SysSetupFormRun\Methods\task.