Mnecraft bug report when click play in other version.

Put the summary of the bug you're having here

What I expected to happen was...:
Describe what you thought should happen here
When click play on Minecraft in a web side, it bugs and comes back to the side i was with a other version.
What actually happened was...:
Describe what happened here
Minecraft side th game online with 1.7.9 version or other. Not Minecraft.net
Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...