If you want to preset the value of any variable object, such as tab control, radio buttons, checkboxes, etc. when a form is loaded, you can use the following technique:

You can use the On Load form event. An example of this is seen below:

Case of
  :(Form event=On Load)
    variableName:=3
End case

Where in this example, we are setting a tab control object and variableName is the variable name of the tab control object. In this particular example, the 3rd tab will be displayed when the form is loaded. You can use this form event either in an object method or a form method.