ScreenCapturer Implements almost QQ's screenshot.

###Module `SCText'

• Occasionally can not hide border and cursor in time,and save the widget appearance incorrectly.

• With GtkTextView, gtk_buffer_apply_tag_* can not apply style to current buffer as expect.

• When selecting top-left of screen, the poped menu & toolmenu can not render background correctly(it seems to rendered with selected region).