Alpha is shipped with a number of pre-set FAQ.SpecialKeys keypress/modifier combinations. One of these is Tab -- pressing this key without any modifiers will (by default) invoke the Next Stop Or Indent function.
To insert a 'real' tab, try pressing Option-Tab.
You can select the
Config > Special Keys
menu item to change the modifier combinations used to insert a Real Tab, as well as the shortcuts to other functions. See the
Help > Electrics Help
file for more information.