Have you been using Enterprise Architect for a while? Do you sometimes think it's impossible to do something in this tool? Maybe you haven't tried hard enough? :)
Let me show some tips and tricks related to UML / SysML modelling using Enterprise Architect.
All examples were created using Enterprise Architect version 16.1.
If you want to reorder messages e.g. move m2 before m1:
You can (as the tool tip suggests) either press Alt key while reordering messages or set one option on the ribbon.
If you want your combined fragment (e.g. loop) to be docked to messages - there is a magic button.
In SysML control flows should use dashed arrows. To enable this notation you need to tick "Dashed line for Control Flow checkbox.