As e-mail-client I'm stick to good old Opera 12.16 - over quite a series of Ubuntu-based distribution versions, up to 20.04. Since this Opera (which is a qt-app) is a quite uninteresting stuff today, I'm showing comparable issues using another example as well: smplayer, which is still part of Ubuntu and Debian packages. I'm going to start with SMPlayer, comparing Linux Mint KDE 18.04 with MX-21 KDE 20.04, which is Debian Bullseye-based. The same appearence problems however also appear on KDE neon distribution (Plasma 5.23).

Here this is SMPlayer settings dialog on MX-21. The Checkboxes appear "classic" while other GUI elements appear okay.

When I change application appearance from breeze to motif, kde app appearances change. But the SMPlayer stays unchanged.

On Mint KDE 18.04 the checkboxes are the same as of KDE apps. Also the appearance changes when I specify e.g. motif or fusion in System Settings! The same applies to the Opera screenshots.


Opera settings dialog window on Neon or MX-21 - several GUI elements appear outdated:


And on Mint KDE 18.04 (as well es older versions) - perfect fit (& reacts on appearance change in System Settings):


That's it. I'm curious if anyone has a hint regarding to getting the appearance as it was used to be.
Plasma old was 5.8.7 and on MX-21: 5.20.5 (while neon uses 5.23).

This entirely depends which libraries were used to build these applications, if those are built with older versions you get older graphics.

I checked the smplayer which is my default since Napoleonic wars. Both on gtk and qt desktops I have no issue getting it to fit the ui. However, in Debian, make sure that you have the smplayer themes package installed. Also make sure that on gtk desktops, the qt5ct settings are done properly. Set it to gtk2 and smplayer appearance settings too. As for the icon theme used in smplayer, you don't have a really extensive choice. Personally I always set it to Breeze. As for Opera, I'm not going to install that, but I'm fairly sure you'd need to have a look at qt5ct in gtk desktops and gtk appearance in qt desktops.

dzon wrote:I checked the smplayer which is my default since Napoleonic wars. Both on gtk and qt desktops I have no issue getting it to fit the ui. However, in Debian, make sure that you have the smplayer themes package installed. [...] As for the icon theme used in smplayer, you don't have a really extensive choice. Personally I always set it to Breeze. As for Opera, I'm not going to install that, but I'm fairly sure you'd need to have a look at qt5ct in gtk desktops and gtk appearance in qt desktops.

I Also have Opera running on a gtk-based machine (Linux Mint Mate). Including qt5ct. It's settings have no impact on Opera. Instead, the native gtk-appearance-settings do affect the appearance. Which - of course - raises the question whether Opera 12 is indeed qt-based. According to available information, it is.

dzon wrote:Also make sure that on gtk desktops, the qt5ct settings are done properly. Set it to gtk2 and smplayer appearance settings too.

I have checked that. smplayer-themes were already installed. Then, In smplayer settings, I found a "style" setting. It was set to "Fusion" (I'd guess it is default). Atfter setting it to "Breeze", the appearance is okay. Thanks for the trigger to verify.

EDIT: smplayer on the older Linux Mint KDE 18.3-version is set to "default", hence inherits the global KDE settings. Then I purged the install on the MX-21 KDE machine, including smplayer-themes; reinstalled and then check, whether the setting is "default" or not. It is. I don't understand why it was set to "Fusion" upon the very first install. I even did not touch settings at all.

Mamarok wrote:This entirely depends which libraries were used to build these applications, if those are built with older versions you get older graphics.

As I pointed out in my response to dzon, the API calls to GUI elements do not refer to any "fixed" Opera internal GUI-library, but rather to OS-related "active" libraries.

When I would be able to install genuinely specified versions of KDE plasma & KDE Frameworks - for example in a virtual test machine, I should be able to identify from which version on the appearence of Opera will no longer depend on the qt5 settings.
I'd appreciate to get a link to information regarding such a interative test of a few KDE versions within the same machine.

Doubt Opera XII is qt. Otter browser is. In either case, smplayer needs to be set in nearly all cases. Haven't seen it otherwise. Not in gtk or qt. I always had to set it manually. Breeze,fusion,gtk,kvantum, lightly....always.

Meanwhile ... I'm quite sure that the root cause is the removal of qt4-related packages after debian buster resp. ubuntu bionic (18.04).

I have just been surprised by the outdated appearance of Openoffice 7 in KDE (from the bullseye repo). Beforehand, I uninstalled by

Code: Select all

sudo apt remove libreoffice*

Note the asterisk.
The outdated view comes in after incomplete reinstallation for KDE:

Code: Select all

sudo apt install libreoffice

The appearance gets right after

Code: Select all

sudo apt install libreoffice-qt5 libreoffice-kde5

Conclusion: Thes packages constitute a sort of API-wrapper, which should be necessary for other programs with outdated appearances as well.

Please report this to Debian, we don't make packages.

Probably my reply was not unambiguous. Originally, appearance of LibO was fully okay. It was my experiment as outlined in that reply that let me surprise about outdated experience. Its only goal is to show that even with up-to-date software, a sort of wrapper packages seems to be necessary in order to get the right KDE-preset appearance-

Still, it is a packaging issue and that definitely is for the distributions to correct.