[lubuntu-users] Strange, dark, look-and-feel of qjackctl, qsynth, and qmidiroute on Lubuntu 18.04

[Israel]

On 1/8/19 5:04 PM, Aere Greenway wrote:
> On 1/8/19 2:07 PM, Israel wrote:
>> On 1/7/19 10:06 PM, Aere Greenway wrote:
>>> Lubuntu Users Group:
>>>
>>> (Sorry - I initially sent this from the wrong e-mail address)
>>>
>>>
>>> To mount my NFS drive on my local client systems, I needed something
>>> to get ask the user for root privilege.
>>>
>>> On Lubuntu 16.04, I used gksu, but on Lubuntu 18.04, that package
>>> appears to be unavailable.
>>>
>>> So in its place, I installed lxqt-sudo, and used that.
>>>
>>> However, after installing that, a number of applications no longer
>>> have their normal Gnome look-and-feel, but instead, have a dark look,
>>> and take up a huge (much more than necessary) amount of screen
>>> real-estate.
>>>
>>> The applications I'm having this problem with, are:
>>>
>>> qjackctl
>>>
>>> qsynth
>>>
>>> qmidiroute
>>>
>>> Does anyone know how I can change them back to their former Gnome
>>> look-and-feel (or even explain what has happened)?
>>>
>>> The strange thing is, on some of my 18.04 systems, this didn't happen
>>> - those applications still have their usual Gnome look-and-feel.
>>>
>>> I have been unable to determine why it is okay on some of my systems,
>>> and not on other systems.
>>>
>>> - Aere
>>>
>> Aere,
>>
>> Those are Qt apps, are you using LXDE or LXQt?
>>
>> If you are using LXDE then, installing lxqt-sudo probably installed some
>> more things, and changed a Qt setting.
>>
>> You can make sure you have the Qt GTK+ engine
>>
>> sudo apt install qt5-gtk-platformtheme
>>
>> This hopefully will fix it.  If not, look for a Qt settings (or KDE
>> settings) in your /usr/share/applications/
>>
>> Then launch this and change it to the qt gtk+ engine
>>
> Israel:
>
> Thank you for your expertise, and your ideas.
>
> I am using LXDE.
>
> I performed the apt install qt5-gtk-platformtheme statement.  It
> indicated the latest version of it was already installed, and the
> newest version.
>
> I launched qjackctl, and it still has the strange, dark, look-and-feel.
>
> I couldn't find anything in /usr/share/applications/ that resembled QT
> settings, or KDE settings.  In Synaptic Package Manager, I searched
> for "kde-settings", "kdesettings", "qt-settings", and "qtsettings",
> but none of those searches found anything.
>
> Is there something I could install that would allow me to change the
> settings?
>
Hi Aere,

I am not 100% sure what needs to be installed, but I found an answer. 
The main thing you need to do is change the Qt theme to use the Qt GTK+
engine.  I am sure there is a way to change the theme from the terminal
(like with GTK), but I don't use Qt as much as FLTK/GTK toolkits.

I found this question on AskUbuntu:

https://askubuntu.com/questions/716714/change-qt5-theme

tl;dr

Use either of these:

lxqt-config

qt5ct

-- 
Regards