Extruding without breaking edge loop I want to model a shape with only quads. 
I created a circle shape and wanted to extrude some vertices away from the curve to form a keyhole. 
I am able to create the shape, but all extruded vertices are not connected to the circle shape anymore and I can´t select the Edge loop via shift-alt-LMB.
I wanted to select the keyhole in an easy way to add a bevel.
Here is how you make a keyhole with all vertices connected.

1) Create a circle (say 32 vertices)
Stay in Edit Mode  

2) Create a plane (also with 32 vertices)
Both the circle and the plane are a part of one object now.

3) Select both loops and connect them with Edge->Bridge Edge Loops
4) Almost done. All inner vertices are now connected into one loop.
5) You can now model you keyhole.

Summary: Edge loops work. It’s all quads.