So you have Qt 5.7.1, unless you have installed a newer version.
My workaround works on Ubuntu 16.04 (with XFCE4 and Qt 5.5.1) and on Ubuntu 17.10 (with Gnome3 and Qt 5.9.1).
Strange that it doesn't work for you
:~$ xnview -platformtheme gtk2
Cannot mix incompatible Qt library (version 0x50902) with this library (version 0x50903)
The error message says that you have on your system a mix of two versions of Qt: 5.9.2 and 5.9.3.
I suggest you uninstall XnView 0.88 (and remove the /opt/XnView directory), then reinstall it, and then extract the lib.tar.gz I provide (this one is for Qt 5.9.2, the version XnView use).
Also double check that you don't have somewhere a 5.9.3 version of libqtgtk2style and libqtgkt2.
sissou wrote:Same problem after these steps - It's strange that it's the only QT app I use that has this issue...
Would be nice if we could do an "ldd /opt/XnView/XnView -platformtheme gtk2" to see what libraries are loaded, but I don't know how to handle the "-platformtheme gtk2" option in the ldd command?
sissou wrote:Same problem after these steps ;-(
Switched to new version 0.89 but it doesn't solve the problem : same error message.
I tried the new version 0.89 and I got the same error message as you. Looking at the files in /opt/XnView for the new version, I saw that Qt 5.9.3 is now used, so I recompiled the gtk2 platformtheme et style libraries with Qt 5.9.3 and this solve the issue for me.
Could you try with this new version of the libraries?
Now that XNView MP's look matches desktop theme, I notice that folder icon don't.
And it should, from what I can read here : viewtopic.php?f=82&t=36148#p144904 :
sissou wrote:Now that XNView MP's look matches desktop theme, I notice that folder icon don't.
And it should, from what I can read here : viewtopic.php?f=82&t=36148#p144904 :
xnview wrote:QT use the current theme
.
Is this the same kind of problem ?
Yes, I have the same issue, from the beginning.
Unfortunately, for now, I don't know how to manage this issue...