From Xojo Documentation
The base class for TextField and TextArea. TextEdit is an abstract class and should not be instantiated directly. Use the TextField and TextArea controls in windows. ListBox.ActiveTextControl is a TextEdit object.
TextEdit is the base class for both TextArea and TextField. TextEdit is an abstract class and it is not intended for instantiation. Use TextArea for multiline and styled controls and TextField for single line text fields.
Execution order of MenuHandlers
The intrinsic control menu handlers (such as TextField.SelectAll) are handled after any user-defined menu handlers on the TextField subclass (if it was subclassed). This means that if you have a SelectAll handler on the Window of the TextField, it will no longer be called when the TextField has focus, because the TextField will now handle it first. In this situation, create a TextField subclass that defines its own SelectAll handler, and handle the desired behavior there.
Use the ValidationMask property to filter user input on a character-by-character basis and add formatting characters. For example, a mask for a Telephone number field can add parentheses, spaces, and dashes as literals, that are used for formatting, and the digit mask symbol '#' to restrict entry to numbers only. See ValidationMask for details.