versioning problems with apt-get build-dep sylpheed

I think I've solved... by using synaptic to install libcairo2-dev, a few dependencies have been ported to older versions and I'm now able to instal build-dep for sylpheed!

I was unable to fix this by manually installing libcairo2-dev. I've even tried it from the live USB. Is there another fix for this?

Trisquel 6.0.1
Can't install libgtk2.0-dev
Error message:

[code]Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
libgtk2.0-dev : Depends: libpango1.0-dev (>= 1.20) but it is not going to be installed
Depends: libcairo2-dev (>= 1.6.4-6.1) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
[/code]

I finally managed to fix this as well using Synaptic, but it was tricky. I had to try to install libcairo2-dev, get an error message. Then I clicked "Mark all upgrades" which included DOWNGRADING libcairo2. After that I was able to install libcairo2-dev and libgtk2.0-dev

Thank goodness! Because I couldn't compile many apps without GTK 2.0

It did not work for me, I will install gnewsense on an external hard disk and build the packages there.