TM Collaboration portal - extensibility issues

Hi ,

I am searching for possible solutions for a client who ask me to enhance its SAP TM standard collaboration portal.

I have then imported the corresponding SAPUI5 application from customer backend to my webide.

I can view the whole application BUT I cannot use the 'New Extension Project' functionality since I get the following message

'There must be at least one view with its matching controller to create an extension project'.

So in this way I cannot go along with my extension project. I guess this is because in the standard implementation of this app the application structure do not have a 'view' folder.

My question now is :

Is it possible to develop custom code extensions using WebIDE OR do I have to do this using SAP GUI from SE80 ?

Kind regards,