From Xojo Documentation
The zero-based way to lookup controls in the window.
All controls on the window are returned as an Object base type. You can use the IsA operator to check the specific type to see if the control is a PushButton, Label, etc.
This example is in the Pressed event of a DesktopButton and displays the name of the first control in Window:
Loop through all the controls on a Window and disable only the TextFields:
For i As Integer = 0 To Self.ControlCount - 1
c = Window.Control(i)
If c IsA TextField Then
TextField(c).Enabled = False