When creating a form, you will want to check that all the parts of the form work correctly. If design mode is off, the form behaves as it would for the end user. Buttons can be pressed, checkboxes checked and list items selected. If design mode is on, clicking on a control item selects it for editing.
Click the Design Mode On/Off button on the Form Controls toolbar to turn design mode on and off.
If the Design Mode button is not available, click on the Select button. This activates most of the tools on the three toolbars.