I noticed that when I try to assign multiple Actions to a widget, the inspector refuse to apply it.
When I try to apply at the Gallery widget the action that when entering the page the property width must be a value of 100 (in fact to full screen), the Action editor does not let me to set Source, Event or Action (they appear in the menu but when selected, the editor clean them).
Actions are grouped by Source and Events. Empty fields in the Action Editor indicate that a Source or Event is equal to the upper action values.
Please see the example with invert size in the attachment.