In the mean time, for users of Mint 17.x KDE, one frustration is that as soon as we go into a non KDE program we end up with tiny little fonts on the screen. In the image above, Synaptic Package Manager is showing with a Font Size of 9, and no amount of fiddling with font settings in KDE System Settigns, > Application Settings > Appearance > Fonts, will fix it. Likewise, changing the settings in preferences in Synaptic makes no difference at all.
There are lots of posts from frustrated KDE users wanting a way to get Synaptic to have fonts consistent with the rest of their KDE desktop. And despite all the weird and wonderful config file suggestions and deleting and reinstalling components, on my system one thing worked perfectly. changing the fonts as ROOT.
Open a Terminal and use the command: kdesudo systemsettings
That will open the settings dialog. In my case, as ROOT, the fonts were all Size 9. My normal system fonts are about size 14 or 16 on my large LED monitors.
Find 'Fonts' in the left pane and choose Adjust All Fonts, and select a suitable size. I chose Size 16 to be compatible with the screen I am using.
Choose Apply, and check the difference in Synaptic.
If Synaptic displays lines overlapping each other vertically, go back and put a tick in 'Force Fonts DPI', then Apply and restart Synaptic. That should fix it.
Here's the Before and After - Font Size 9 as default, and Font Size 16 after. Much nicer to work with.