Any property to set to make textbox to resize according to the window size?
It could be little tricky because of few constraints.
I tried this solution which makes your width bounded to parent ( I agree there could be better solutions as well, but this was easy and worked fine)
FIX message...
So only good thing I did was, I binned the
Width= "{Binding ElementName=LeftColumnDefinition, Path=Width}"
to