Improve support for detection of shortcuts which are browser shortcuts

[seekshiva]

Improve support for detection of C-W, C-T and such shortcuts which are also browser shortcuts. General shortcuts such as C-S, C-A are all detected by the script.. but shortcuts which involve browser tasks such as opening a new tab(C-T), closing the current browser window(C-W), opening a new window(C-N), etc are overridden by the browser. This will have to be captured and the default action must be prevented