How can I make text in meld readable?

Question

A few months ago, meld started behaving oddly. Common lines are almost unreadable, and shown as dark grey text on a black background.

Oddly enough, running it as root is fine (with kdesudo meld), although the theme is less pretty.

How can I specify the text's colour options for meld?

I'm using:

• Arch Linux
• KDE 4.14.3 (also seen in 4.14.2)
• meld 3.12.2 (also seen in 3.12.1)
• gtk3 3.14.6 (also seen in 3.14.5)

Troubleshooting

KDE system settings

meld uses GTK3, so I fiddled with System Settings > Common Appearance and Behaviour > Application Appearance > GTK > Select a GTK3 Theme. This change was reflected in meld, but none of the three options I selected changed the text. (The available options were Default, Emacs, and oxygen-gtk; the latter is used in the screenshot above.)

Manually modifying config files

I looked in ~ for files with gtk in their name.

~/.gtkrc-2.0
~/.gtkrc-2.0-kde4
~/.config/gtk-2.0
~/.config/gtk-3.0
~/.kde4/share/config/gtkrc
~/.kde4/share/config/gtkrc-2.0

Interestingly, there is nothing with gtk in its name in /root. Hence, I tried deleting some of the ~ files, to see if I could get the same effect for my user. I presume all the gtkrc-2.0 files are irrelevant to meld.

Firstly, I deleted ~/.config/gtk-3.0, but this had no effect, and was recreated when I opened meld.

The only other option appeared to be ~/.kde4/share/config/gtkrc, so deleted this and started meld, which was unaffected. However, the file was not recreated, and it contains some possibly pertinent lines (e.g. text[ACTIVE] = { 1.000, 1.000, 1.000 }). I'm unsure if the (missing) file was loaded at all. I tried kbuildsycoca4 ; kquitapp plasma-desktop ; sleep 2 ; kstart plasma-desktop, but this had no effect. Do I need to manually reload the gtkrc? And why is this file not being affected/rewritten by the system settings?

(Also, FWIW, I removed ~/.gtkrc-2.0-kde4, which was actually a symlink to ~/.gtkrc-2.0, and I also removed the target itself, but that didn't help. Again, I didn't reload gtk (I'm not sure if this is necessary, or possible), and the files weren't re-created when I tried running meld again.)

Possibly pertinent environment variables

$ export | grep -i gtk
declare -x GTK2_RC_FILES="/etc/gtk-2.0/gtkrc:/home/sparhawk/.gtkrc-2.0:/home/sparhawk/.kde4/share/config/gtkrc-2.0"
declare -x GTK_IM_MODULE="xim"
declare -x GTK_MODULES="canberra-gtk-module"
declare -x GTK_RC_FILES="/etc/gtk/gtkrc:/home/sparhawk/.gtkrc:/home/sparhawk/.kde4/share/config/gtkrc"

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(Disclosure: I've previously asked this question on the KDE forums, but didn't come to a solution.)

Answer 1

At least from Meld 3.16.4 support different color schemes.

See Meld > Preferences:

(possibly this change was introduced in earlier versions)

Note:
It is also possible to force a specific theme for Meld by CLI: GTK_THEME=Adwaita:dark meld

Answer 2

only leting a update...

The 3.18 version will not show preferences to change your theme.

but by dconf-editor, you can access the meld configuration and set style-chema to 'meld-dark' ... and be happy!

almost like that: https://linux.m2osw.com/no-meld-preferences-menu

Answer 3

If I do locate -b meld | grep home, I get three directories you haven't mentioned;

~/.gconf/apps/meld
~/.gconf/apps/gnome-settings/meld
~/.local/share/meld

The one in ~/.local/share just seems to be a history of local comparisons, but the other two directories have xml files in them. I would try removing those.

If that doesn't work, you can see exactly which files meld reads with something like:

strace -e trace=file meld |& grep home

Looking at the output will should hopefully yield something else to investigate.

Failing that I would try creating another user account, logging in and running meld (but nothing else) there. If it displays ok, you could view the dot files/environment variables there and compare them to your own account. Note that you should log in via X and not just use su or sudo so that your desktop environment gets the chance to create the default dot files - this will likely be why it looks plain when running as root.

If none of that works, you could always give up and use Diffuse instead. I haven't tested it properly yet myself, but it does some things that meld can't (no directory comparisons though, so not quite a replacement). :)

Update

To try to track down the offending file(s) you can compare the dot files in the new account with the old. Unfortunately it could be almost any of the dot files in the new account, which is why it is important not to run any other applications (especially a web browser) as this will create/change more. To compare files you could try running something like this in the new account:

find . -type f -exec cmp {} /home/your_account/{} \;

For the ones that are different, you could investigate further with, er, Meld. If this doesn't yield anything then there is probably a file that you want to remove which would be hard to find. You could try going back to strace and comparing the outputs from the two accounts.

Answer 4

It looks like it was a regression introduced in Meld 3.12.1. I downloaded previous versions from the meld website.

Meld 3.12.0 works fine.

Meld 3.12.1 does not.

I contacted the devs and they told me that it was indeed a regression introduced in the gtk+ 3 port. They suggested trying the just-released 3.12.3, which now works. (However, it still doesn't fully explain why meld in a new account would work.)

Answer 5

overwrite the meld.css with the one there and you will be able to use Meld with the dark theme https://wiki.gnome.org/Apps/Meld/DarkThemes