I want to update minecraft 1.6 for my mac vesion. I get a bar saying there is a bug lwjgl and is not compatible with my version 10.5.8

Put the summary of the bug you're having here
I can update minecraft 1.6
What I expected to happen was...:
Describe what you thought should happen here
I was expected to have the new version of minecraft.
What actually happened was...:
Describe what happened here
I got a bar saying is not compatible with mac 10.5.8 bug lwjgl
Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...I download laucher from minecraft page.
3. ...I got the bar of error.