Can not create Protected Area if some cells are already in other Protected Area
Steps to reproduce:
1. user1 create a new excel file in Docs, share to user2 and user3 as Editors.
2. user1 select the whole 2nd line of the file, assign "Editable" right to user2 for the Protection Area.
3. user1 select the whole F column of the file, assign "Read only" right to "Everyone except me" for the Protection Area, but failed with a window:
--Title: "Your changes cannot be saved."
--Content: "The changes you made were in a range that is protected."
The F2 cell is already in the 1st Protection Area, so it can not be in the 2nd Protection Area.
Prompt a window: F2 is already in other Protection Area. Override? If select Yes, then override the 1st Protection Area for F2 cell. If select No, then does not override the 1st Protection Area for F2 cell.
Scenario for this enhancement request：
F column is summary column which is a computing formula, not allowed to modify, so set it to read only.
There maybe several summary columns in one line, and they are not at the last columns.
Each user can only modify one line that he owns, but he can not modify the summary columns in the line.
So the problem is, when user set the summary columns to read only, he can not set Protection Area to each line.