Sometimes a mod needs to handle a keyboard/mouse/controller button without letting the game handle it too. For example:

• when clicking an overlay shouldn't pass through to what's under it;
• when pressing a key combination that shouldn't also trigger the default bindings.

Add a way for mods to suppress button input so the game can't handle it. This should not prevent other mods from receiving the input event.

Done in develop for the upcoming SMAPI 2.0 release.