Im in the process of the same job, and I am considering (have not decided yet) using 3M 560 or 540. 3M says:
3M™ Scotch-Seal™ Polyurethane Sealant 540 and 3M™ Scotch-Seal™ Polyurethane Adhesive Sealant 560 are one component, moisture curing products which form permanent elastic bonds. They bond to a wide variety of materials including plastics, FRP, SMC, aluminum, steel, coated metal, and wood.
Here is all the data:
The only catch is I only see 540 on sale on their web site, can't find 560. 3M says that 560 has a tensile strength of 580psi and an elongation before break of > 300%. For windows that might be a good strength, although if you want less than the 540 has 250psi and > 800%.
I can't say I know just how strong a dead light bond should be, hopefully someone who knows will chime in