I open my launcher on a windows 7 laptop, no problem, i can create new worlds in 1.7.9 and for exaple ad a seed and change type of world without a problem, And i can create a new world in snapshots as long i don't press the "more world options..." button.
From the moment i click that button it goe's to the right "page/screen" but when i hover over a button it doesn't turn blue, when i click it it turns blue after half a second but there's no clicking noise or a change. there's no cursor to type a seed if i click on it everything just sort of freezes. i can't press done, somethimes when i press cancel it does cancel afther a while.
This only happens when i use any snapshot i've testet so far (the last 3 snapshots)
i noticed this when 14w10c came out but i tought you would patch it in the next one. when i wanted to test the costumiseble world i saw it wasn't fixed.
After having this issue:
Please attach the complete output of the "Development console" which can be found on the second tab of the launcher.
If the launcher closes after game start, please edit your profile and select "Launcher visibility" then, "Keep the launcher open".