If anyone has used the Code::Blocks IDE you would know you can colapse sections like
1if(x == y){
2XXXXXXCodeXXXX
3XXXXXXXXXXXXXXX
4XXXXXXXXXXXX
5XXXXXXXXXXXXX
6XXXXXXXXXX
7}
8
to become
1if(x == y){
-----
7}
this would be a very helpfull feature for large amounts of code
Even better, possibility to use several files at once inside the IDE. 
Even better, possibility to use several files at once inside the IDE.
This capability has existed for several versions - at least since 0013. Separate tabs are opened for each file in the directory with the sketch. A button allows you to create a new tab/file.
Ok... my bad.