when user click close button to close a document which is modified and not saved,there should be a messagebox asking whether to save or not save or cancel .
if user choose cancel ,the document should not be close,but the TabBar remove the tab of the document.
when user click close button to close a document which is modified and not saved,there should be a messagebox asking whether to save or not save or cancel . if user choose cancel ,the document should not be close,but the TabBar remove the tab of the document.
Signed-off-by: foniova z.liangyi@gmail.com