problems with gwt in ubuntu linux

I have long wanted to start learning GWT (Google Web Toolkit), but there was no time at all. I found a couple of hours today.
I downloaded the latest version of GWT-1.7.1.
Here is the simplest Hello World with a button. When launched, it throws an exception
[java] ** Unable to load Mozilla for hosted mode **
gwt-linux-1.7.1 / mozilla-1.7.12 / libxpcom.so: libstdc ++. so.5: can not open
shared object file: No such file or directory

The latest version of GWT uses the library libstdc ++. So.5, which is strange because it is now version 6.
In standard reps, this one was not there and I had to look for it.
The solution to the problem was found:
wget es.archive.ubuntu.com/ubuntu/pool/universe/g/gcc-3.3/libstdc++5_3.3.6-17ubuntu1_i386.deb
mkdir tmp
mv libstdc ++ 5_3.3.6-17ubuntu1_i386.deb tmp
cd tmp /
dpkg -x libstdc ++ 5_3.3.6-17ubuntu1_i386.deb libstdc ++ 5
cd libstdc ++ 5 / usr / lib /
sudo cp libstdc ++. so.5.0.7 / usr / lib
cd / usr / lib
sudo ln -s libstdc ++. so.5.0.7 libstdc ++. so.5

PS It's interesting why is libstdc ++ version 5 used?