Just check this fiddle:
How can I stretch the blue div 100% horizontally so it docks to the purple right div?
If I set width:100% its just doing what a div is used for to "line-break" down the purple div.
I also tried display:inline(-block) nothing helped to make the purple div stay on the same
line as the blue div.
The solution must work on IE9. Please no CSS3 hacks.