You can type controls. in a script, and a list of all controls in the form will appear to help you:
If this disappears, you can bring the Intellisense back by placing the cursor to the right of the full stop and pressing Control and Space.
You can perform actions associated with a particular control with a full stop after the control name. For example, to show or hide a control you would use:
controls.my_control.show();
controls.my_control.hide();
Control names are case sensitive. If you try to access a control named 'my_control' with the code controls.My_control an error will occur.