Change the method of making flat dialog

Before, I use ModifyStyle() funciton to make flat style. But I think
override the NcCalcSize() method, so I changed this.
Fix some crashed design and bugs

After apply flat style, applied diaglos' design crashed. So I rearrange
the controls.
And sub dialogs' size of setting dialog has not proper size and
position, so fix them. Furthermore, finder button has no SizeToContent()
and fix that.