It seems that the Zoom Factor widget only uses integer factors greater than 2. 
However, that requirement isn't communicated effectively through the way the 
widget behaves and the error messages it produces. 

If you enter "4.e" as input, then try to do an action, are error message comes 
up with "Value entered is not an integer". and the action is halted. 

However, if you enter "4.2" (which is not an integer), then try to do an 
action, no error message appears and the action is performed. The value in the 
field remains "4.2", but the zoom factor used is actually 4. 

If you enter "-4" (which is an integer), you get the error message "Minimum 
Zoom Factor is 2". Then the value is automatically changed to 2.

These different behaviours are confusing taken together. 

I would suggest the following as a solution:

* If input value is not an integer value 2 or greater, then pop up a single 
error message "Value entered must be an integer greater than 1".

  * If the errant input value is a non-integer number greater than 2, then 
automatically truncate the value and change the field. 

  * Otherwise, automatically set the value to 2 and change the field.

* Otherwise, leave the value as it is.