Hi, there is a way to launch MATLAB editor from a standalone desktop aap. You just need to add the below line to your button / startup callback.
!matlab -nosplash -nodesktop -minimize -r "edit"
It creates a new instance of MATLAB and launches the Editor.
Download to the attached .zip file and refer the .mlapp and the standalone .exe file. You can tweak various parameter according to the this and this documentation to make it behave the way you like.