Why is the File Name field grayed out when I enter the Save Transform command? (Version 11 and earlier)

Users can save their current transformation matrix under Tools>Transform>Save Transform.

To populate the File Name field, press the Save Matrix button. In the browsing window that appears, navigate to a desired save location and enter a file name.  After pressing the OK button, the File Name field will be populated.  Then click OK in the command to exit.