Merge pull request #55 from nongxiaoming/master

1.fix the edit bug when edit is empty,the insert line function is not wo...
Merge remote-tracking branch 'xiaonong/master'
Merge pull request #57 from nongxiaoming/master

optimize the rtgui_theme_draw_radiobox function
use RT-Thread list to replace dlist in rtGUI
Fix compiling warning in GCC
widgets: window: hide window on modal window exits
topwin: fix _draw_tree

When drawing the children, we should draw from the left child.
widgets: filelist_view: avoid page_items to be 0

If it becomes 0, there will be divide by 0 error.
widgets: filelist_view: fix the folder callback crash

rtgui_listbox_set_current_item will invoke the "onitem" callback. So
just keep it clean when setup the initial state.
demo: fix the demo_listview
demo: bring back the demo_fnview
widgets: listbox: misc code format
widgets: filelist_view: optimize the icon usage and fix a mem leak

All the icons in filelist_view are identical, so it should only need to
be created at the first instance startup.
widgets: filelist_view: misc code format
widgets: filelist_view: remove the "exit" entry

"Exit" a widget does not make any sense.
widgets: filelist_view: add ".." entry manually

"readdir" is not guaranteed to return ".." entry. So we have to add it
manually.
widgets: filelist_view: close button on menu is not needed
Code cleanup.

Change the code style and make more clean for indentation.
Support the button disable feature.
Update .gitignore file.