References:
KDE Bug #347459
KDE Bug #344638
Qt proposed patch
This bug was fixed in Qt 5.5.0, but of course Ubuntu won't repackage the newer Qt library until the next version comes out, which is months away. Until then, fuck you.
I'm sure there is a better way to accomplish this that won't cause trouble when I upgrade my Ubuntu revision-level, but I couldn't find it. And this definitely solved the problem. If you know of a better way, feel free to explain it in the comments.
Goal: install Qt 5.5 and make KCalc use it, but don't screw everything else up.
Step 1: Download and install Qt Creator 5.5.
You can do this is a non-root user. Go to the Qt website, and download Qt Creator. You can either step through their question and answer screens to assure them that you're not planning on breaking the LGPL, or simply use this link: Qt Creator Open Source Download Be sure to select the binary that is right for your version of Linux (32-bit or 64-bit). When you run the installer, go ahead and skip the Qt Account creation. This is more for developer users of Qt, which you are not. "Next" your way until it asks what components you want to install. You want these (yes I know my colors are wacky, deal with it):
Note that Tools/Qt Creator will also be selected and you can't unselect it. "Next" along and wait for the download to finish. Now you'll have a folder in your home directory, probably ~/Qt/, that contains the Qt 5.5 product set.
Step 2: Put the libraries somewhere accessible.
As root, copy the libs downloaded from Qt into /usr/local/lib/Qt5.5/. Assuming you stored it in ~/Qt/ during Step 1, the commands would be:
sudo mkdir -p /usr/local/lib/Qt5.5
cd ~/Qt/5.5/gcc_lib64/lib
sudo cp * /usr/local/lib/Qt5.5/
cd ~/Qt/5.5/gcc_lib64/lib
sudo cp * /usr/local/lib/Qt5.5/
By putting them in /usr/local/lib, we're keeping them out of the upgrade path of apt-get and its brethren. This means you need to disconnect this hack once 15.10 comes out, but security updates shouldn't have any freak-outs in the interim.
Step 3: Have KCalc, and only KCalc, use the new libraries.
As root, edit /usr/share/applications/org.kde.kcalc.desktop. This is the system-wide launcher for KCalc, and is used as a base whenever the user customizes anything using the menu editor. Look for a line that says:
Exec=kcalc
Replace that sucker with:
Exec=LD_LIBRARY_PATH=/usr/local/lib/Qt5.5 kcalc
This causes Linux to set the LD_LIBRARY_PATH variable to point to your Qt 5.5.0 libraries before any other shared-library pathing is done. This is a hack, but it's the best you have unless you want to start recompiling things.
If you have already modified KCalc (changed its icon, etc) in the menu editor, look for a file with the same name in ~/.local/share/applications/ and make the same changes to it as well. If you have multiple users on your system, do them a favor and run a quick find on the /home tree and update any custom files they have, too. Or chuckle when they can't use the keypad. Whatever suits your personality.
