Save undo stack during macro run - vba

Question

I am wondering if there is a way to save ability to undo actions after macro has been run.
I do not care about results of macro - just need to undo actions that were done by user before macro.
Background:
I have a macro on the worksheet_change event that logs who and when made the change on this worksheet. I do not want it to restrict user's ability to undo his/her actions.

Answer 1

There is no easy way to do this, but it's possible. The approach to this is to create three macros, and use some global variables to save state:
MyMacro
MyStateSavingMacro
MyStateRevertingMacro
E.g. My macro changes Cells in Range A1:A10 of the active sheet. So, whenever the code to run my macro is called, it executes
Sub MyMacro()
Call MyStateSavingMacro()
' Copies contents and formulae in range A1:A10 to a global data object
'... Code for MyMacro goes here
'
'................
Call Application.OnUndo("Undo MyMacro", "MyStateRevertingMacro")
'This puts MyStateRevertingMacro() in the Undo queue
'So pressing ctrl-Z invokes code in that procedure
End Sub
Sub MyStateSavingMacro()
' Code to copy into global data structures anything you might change
End Sub
Sub MyStateRevertingMacro
' Code to copy onto the spreadsheet the original state stored in the global variables
End Sub
So there it is. It's not pretty, but can be done.
Ref: http://msdn.microsoft.com/en-us/library/office/ff194135%28v=office.15%29.aspx
Edit:
To preserve the Undo queue prior to your MyMacro being run, the inelegant solution would be to create a chain of 4-5 MyStateRevertingMacro_1, _2, etc. where you can apply the information from your Worksheet_Change logging system and then chain-up the Application.OnUndo in each of those, so Application.OnUndo for each of those Reverting Macros would refer the previous state reversion code.

Answer 2

You can use the hidden mirror sheet to do this. Of course it will work if your worksheet is simple enough. You must decide which cells are editable and copy them TO mirror sheet, which are not editable and copy them FROM mirror sheet. And your macro should work only in the mirror sheet. That's it.

Answer 3

This one is a bit old now but in case anyone is still trying to get this to work - I just tried setting the undo stack to be able undo the formatting on a column that a macro had reformatted and noticed that by doing that the full undo command worked (before I added this bit the undo was unavailable) - does not matter what the custom undo code contains (in my case I had not even created the routine yet), the application undo works perfectly
Application.OnUndo "Undo Amount Format", "sUndo_Col2"