id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
2763	Undo/Redo system porting from v2	Garry Yao	Frederico Caldeira Knabben	"Undo/Redo system need to be ported from v2, the features could be summed up as below:
 * Undo system restore/retrieve document status from both selection and content     
 * All commands that modify the document could support undo/redo feature,but each command has chance to optionaly declare whether would hooked with undo systemwhen they're registed.
	  '''Note''': Since from v3 all keystroke will pre-bind to command, so keystrokes also hooked with undo system through command interface.
 * Undo feature itself performed as a command, A button plugin is required for interfacing this command to end user and keystroke pair of 'Ctrl-Z' and 'Ctrl-Y' too.
 * Support empty/reset all the undo snapshots for clean up,  and A button plugin is required for interfacing this ''reset''
 * snapshot for undo system could be recorded in two forms:
  1. One snapshot for each record action, this apply for almost every functional commands, but a few special keystroke commands that also being recorded in this way including:
   a. 'Enter'
   a. 'ShiftEnter'
   a. 'CtrlBackspace'
   a. 'Delete' 
   a. 'Tab'
   a. 'Ctrl-X'
   a. 'Ctrl-V'
  2. One snapshot for a serials of record actions, this apply for most keystroke commands. 
 
Test cases ported from #915 :
 *  
 {{{
 1. Select text, change style, undo
   Expected results: 
   - text style restored, 
   - selection restored.
 
 2a. Type one ANSI charater in the editor after it's loaded
   Expected results: 
   - undo button is enabled, 
   - undo can be performed by clicking the toolbar button
   - undo can be performed by Ctrl-Z
 2b. Undo once
   Expected results: 
   - redo button is enabled,
   - redo can be performed by clicking the toolbar button 
   - redo can be performed by Ctrl-Y
   - previous contents restored
   - previous caret position restored
 2c. Redo once
   Expected results:
   - undo button is enabled, 
   - undo can be performed by clicking the toolbar button
   - undo can be performed by Ctrl-Z
   - changed contents restored
   - changed caret position restored
 
 3. Type more than 25 ANSI characters in the editor
   Expected results:
   - One undo level should be generated for every 25 characters typed
 
 4. Pressing Ctrl-Z repeatedly after the undo button greyed out
   Expected results:
   - Nothing visible happens
   - Undo/redo system should still work normally afterwards
 
 5. Pressing Ctrl-Y repeatedly after the redo button greyed out
   Expected results:
   - Nothing visible happens
   - Undo/redo system should still work normally afterwards
 
 6a. Select some text, Ctrl-X, repeat N times
   Expected results:
   - The selected text blocks are cut
 6b. Undo once
   Expected results:
   - The last cut operation was restored
   - The selection or caret position was restored
 6c. Undo N-1 times
   Expected results:
   - The cut operations were restored in a step-by-step manner
   - The selections or caret positions in each step were restored
 
 7. Repeat 6a-6c with Del and Ctrl-V
 
 8a. Toolbar commands that change the document
   Procedure:
   - Select a toolbar command that changes the document (e.g. insert smiley)
   - Carry out the neccessary steps to make the change effective (e.g. choose smiley, ok)
   Expected results:
   - One undo step is generated after the change
   - Ctrl-Z or clicking ""Undo"" undoes the change
   - Ctrl-Y or clicking ""Redo"" after the previous point redoes the change
 8b. Repeat the ""procedure"" part of 8a to repeat the same change to the document N times
   Expected results:
   - N undo steps are generated after the changes
   - Ctrl-Z/Undo button and Ctrl-Y/Redo button would undo/redo the changes in a stepwise manner
 9a. Pressing Ctrl-Z breaks the undo/redo system
 }}}"	New Feature	closed	Normal	CKEditor 3.0	General		fixed	Confirmed Review+