There is a known bug in CatTools which could result in the Edit screen seemingly not opening or is misisng when the Add or Edit buttons are clicked.
Kiwi CatTools 3.10 and earlier
This bug typically affects multi monitor displays or multi user environments and occurs because CatTools isrestoring the last known position of the window without checking to see if that position was valid for the current system configuration.
A fix for this has been applied in version 3.1.0 and later.
If you have a version prior to this and do not want to upgrade, you can resolve this problem by opening and editing the
KiwiCatTools-Settings.ini file which can be found in your CatTools installation folder.
Delete the following lines, or reset their values to 0 before saving.