Retrieves the last undo reason. 
- Returns
 One or combination of the following values: Action types:
- g_dwUATUndefined: unknown type
 
- g_dwUATInsertData: data inserted
 
- g_dwUATDeleteData: data deleted
 
- g_dwUATIndentData: indentation
 
Action reasons (more exact types):
- g_dwUATTyping: typing
 
- g_dwUATCut: cut
 
- g_dwUATPaste: paste
 
- g_dwUATDelete: delete
 
- g_dwUATBackspace: backspace
 
- g_dwUATDragDrop: drag & drop
 
- g_dwUATEnter: new line (return key)
 
- g_dwUATIndent: forward indentation
 
- g_dwUATUnindent: backward indentation
 
- g_dwUATTab: tabulation
 
Call this method to retrieve the last undo reason. Every time the text in the edit control is changed, the new undo action is added in the undo buffer. Actually, the undo reason indicates the last action that was performed.