WebAPI/BrowserAPI/KeyboardEvent

Dispatch KeyboardEvent across BrowserElements

This is a proposal to enable applications to handle/override the behavior of certain KeyboardEvent.

There are four scenarios which should be fulfilled:

Scenario	Description	Example Keys
SYSTEM-ONLY	For keys which should be handled by mozbrowser embedder iframe only.	'Power', 'VolumeUp', 'VolumeDown', 'VolumeMute', 'DisplaySwap'
SYSTEM-FIRST	For keys which can be handled by mozbrowser embedder iframe first and can also be handled by mozbrowser embedded iframe then.	'Info', 'Settings'
APP-ONLY	For keys which should be handled by mozbrowser embedded iframe only.	'ColorF0Red', 'ColorF1Green', 'ColorF2Yellow', 'ColorF3Blue', 'ColorF4Grey'
APP-FIRST	For keys which keys can be handled by mozbrowser embedded iframe first and can also be handled by mozbrowser embedder iframe then.	'Info', 'Settings'

Note that some keys could be either SYSTEM-FIRST or APP-FIRST. The behavior is decided by the author of applications.

Four new events are proposed:

• mozbrowserbeforekeydown
• mozbrowserkeydown
• mozbrowserbeforekeyup
• mozbrowserkeyup

Concept diagram

When a key is pressed down, the event sequence would be:

1. 'mozbrowserbeforekeydown' is dispatched to mozbrowser-embedder iframe
2. 'keydown' is dispatched to mozbrowser-embedded iframe
3. 'mozbrowserkeydown' is dispatched to mozbrowser-embedder iframe

Similarly, when a key is released, the event sequence would be:

1. 'mozbrowserbeforekeyup' is dispatched to mozbrowser-embedder iframe
2. 'keyup' is dispatched to mozbrowser-embedded iframe
3. 'mozbrowserkeyup' is dispatched to mozbrowser-embedder iframe