this will avoid call any method when model deleted, if not, peony might crashed.

fixme: deal with fast keyboard locating.

1.Advance serach type choose has no effect because of the default search type is all.
2.Fix spell error of key.

IconView: fix the unexpected rubberband when dragging to select a file and then try dragging this file.

note that this is a complex process and only can worked in peony frameworks.

The new process should be more reasonable, because there might be some unexpected cases
that let item enumration not finised due to query info failed by somehow.

1. dirived from QWidget and do layout by ourselves.
2. interactions about location jump and cd up become more friendly.

1. add context menu for location button, (#206).
2. draw border with base color, not dark or highlight.