Fix keyboard shortcuts not caught when iframe is focused/clicked

[ronjouch]

Not sure it's possible, current workaround is to unfocus the iframe (i.e. click anywhere else).

Technical cues:

• http://stackoverflow.com/questions/2161388/iframe-function-calling-from-iframe-to-parent-page-javascript-function
• http://stackoverflow.com/questions/3381920/how-can-i-pass-attribute-value-from-iframe-to-parent-in-javascript