Find box - backspace required for user to perform search another item

[Angus Yeh]

When user use find box after the 2nd time, current behaviour requires user to delete text (by backspace) to find another item. It can be improved by selecting all text when back in focus.

[Angus Yeh]

Fix Issue #37 by select text when find box gets focused. (By installing event filter)

→ <<cset 5cb3a1780f73>>