F9 window: make appear BEFORE tool is applied

The F9 window ("Adjust Last Operation") could appear BEFORE a tool is applied, inheriting the last values used for that tool. This would give users an opportunity to re-use the same values (yes, I know about "Repeat Last", this is a >visible< way to do that).

To avoid situations where the values would be 'way too small/large for the new operation (which could result in the selected geometry going off-screen), the operation would not occur until A) the user clicked an "APPLY" button in the F9 window, OR B) the user used the mouse in the 3dView to use the tool in the usual manner, at which points the new values would be entered into the appropriate F9 fields.

This is a type of 'security blanket' for users, so they can see the values "Repeat Last" is using.