I noticed that Developer accepts all solutions te be added as modules.
No matter if they have ‘module’ as solution type.
Solutions added as a module to another solution (from the tree) keep there original solution type property (the renaming has to be done manually).
You might want to have a solution that can be run independently, but also as a module of another solution. In this case it will have a SOLUTION type, although it is also a module. That is why the type is not changed automatically.
Here is how solution type works:
in web client you can open solutions of type SOLUTION and WEB_CLIENT_ONLY.
in smart client you can open solutions of type SOLUTION and SMART_CLIENT_ONLY.
If you do not want a solution to be accessible independently of other solutions , you should mark it as a module.