Window.Control
From Xojo Documentation
Method
The zero-based way to lookup controls in the window.
Notes
All controls on the window are returned as a the Control base type. You can use the IsA operator to check the specific type to see if the control is a PushButton, Label, etc.
Example
This example is in the Action event of a PushButton and displays the name of the first control in Window:
MessageBox(Self.Control(0).Name)
Loop through all the controls on a Window and disable only the TextFields: