Did you know that you can show States and Submachine States of Statemachine diagram and Actions and CallBehaviorActions in Activity diagram in the Structure Tree?
To do so,
(1) Go to [Tool] – [System Properties] and select [Project View] from the left menu
(2) Check the option [Show States and Submachine States on the structure tree] or [Show Actions and CallBehavior Actions] on the structure tree] and then click [Apply] – [OK].
Take a moment to browse the System Properties ([Tool] – [System Properties]), there may be options that you were looking for and changing them can make Astah much easier for you to work with!