It would be nice to have text object outline and drop shadow effects.
it would be nice if that is done with a shader system than can apply shader effects to any object - not just text. 
You can sort of fake shadow with two text objects. Both have same font and size, but one is white and the other is black. White text has higher Z index so it’d be drawn on top. Also white text object is a bit moved in relation to black so it pops out.
Don’t know such a trick for an outline, sorry.
Yeah, that’d be great. But even if we’d get shader support, not everyone is able to do shaders. I, for example couldn’t figure out GLSL even if my life would depend on it. Even though I’ve tried to do so so many times - the only way I can “sort of” make shaders is with node editors such as one in UDK or UE4.
If you make it easy to add ready shader code to an object or a layer, to get access to some of its public variables,
Then you need only a few experienced users to share their shaders and everyone else will benefit!
Just look as an example construct2’s forum:
scirra.com/forum/effects_f184
People are writing and sharing shaders like crazy over there. Some of the shaders made it in the engine’s official builds too!!
Those are webgl effects. Make gdevelop compatible with the community webgl effects of construct2 and we suddenly get access to a whole lot of content that has already been implemented and tested!