Posibly a stupid question...

[ampos]

I just installed GLB.

I load a demo, hit F5 and OK. Fine.

Load another demo. Press F5, and it runs the previous demo.

No matter with demo I load, F5 or F8 just run the very first app I loaded.

It should be stupid, but I got no clue how to.

[François Vanzeveren]

How did you load the second demo? You should use "File > Project > Open"

[hardyx]

I think you loaded a single .gbas file instead the project (.gbap).