CUPS backends not found after upgrade

Recently I upgraded CUPS package in my Debian. The version is now 2.0.3-10 but maybe it is not relevant. After the upgrade I had encountered a printing problem: the defined printers were not present in list. OK, I had to reinstall all the CUPS and related packages (foomatic, hplip, ...) - unfortunately I don't know which all. When all this pain was done, I was able to see the printers in the list once again. BUT: the window showing the printers said:

Backend /usr/lib/cups/backend/socket does not exist!
Backend /usr/lib/cups/backend/hp does not exist!

Google around for couple of hours and tried many different solutions. Finally I found this thread and that was it. No permission setting on /usr/lib/cups/backend/hp or parent directories was necessary. Only to invoke this command under root:

cupsenable Canon-iR-ADV-C5235-5240

Post mortem I realized, that the strange scratches through the printer icon (see the image) were not the error of the graphics driver but notification about CUPS disabled device.

Now I am about to find why the printer manager window freezes when I try to click on printer properties :)

By the way, the folder /usr/lib/cups/backend should have the proper rights:

drwxr-xr-x 2 root root 4096 lis 16 16:06 /usr/lib/cups/backend

Gluegen compilation with ANT

I have just spent two days googling and trying various things to compile Gluegen. Every time I ended with message

BUILD FAILED
/scratch/hanousek/gluegen2-2.0-rc5/make/build.xml:627: The following error occurred while executing this line:
/scratch/hanousek/gluegen2-2.0-rc5/make/build.xml:156: Problem: failed to create task or type antlr
Cause: the class org.apache.tools.ant.taskdefs.optional.ANTLR was not found.
        This looks like one of Ant's optional components.
Action: Check that the appropriate optional JAR exists in
        -/software/ant-1.9/1.9.4/lib
        -/root/.ant/lib
        -a directory added on the command line with the -lib argument
Do not panic, this is a common problem.
The commonest cause is a missing JAR.
This is not a bug; it is a configuration problem

Of course I had tried to install ANTLR, ATNLRv3 and even ANTLRv4, but with no success. Things like

ant -Dantlr.jar=/software/ant-1.9/1.9.4/lib/antlr.jar -Djunit.jar=/software/ant-1.9/1.9.4/lib/junit-4.11.jar

didn't work so don't spend a lot of time with that.
The solution is finally quite simple. Developers says that it should work with ant >= 1.8. This is wrong, at least for version 1.9.4 which I had installed. When I tried to use ant-1.6 and edited file make/build.xml to remove the ant version requirement section, everything went OK.

PSI and SSL in Debian

When you want to use a SSL/TLS plugin in jabber client PSI in Debian, you should have installed the qca-tls package.

Compiling documentation

When an error

Unknown option -force_html

appears during compilation or configuration of any documentation (for example of package xorg-doc), it means that you should have the lynx package installed.