The attached zip file contains the simplebrowser example project with a one line change:

newTabAction->setShortcut(QKeySequence(QLatin1String("c")));

If you run the project, wait for the Qt website to load, and click on the search button on the right, then type "abc", you'll see that only "ab" will appear, and a new tab will open. The c character never seems to make it to the input element in the webview, instead being swallowed by the shortcut. WebKit behaved differently in this case - if an input element was focused then the key would go to the input element, and the shortcut would only fire if there was no active input element.

Aside from breaking single character shortcut keys (like gmail shortcuts), it also breaks ctrl+z in a text field to undo the current typing, if the application has a different behaviour for ctrl+z when no input is focused. And same with ctrl+a for select all in the input area vs something else when no input is focused.