How to enable dark mode in gambas qt5 application in ubuntu?

[Safiur Rahman <isafiur@xxxxxxxxx>]

Hi

I have Ubuntu 22.04 OS (XDG_CURRENT_DESKTOP=ubuntu:GNOME). The widget-theme
is Yaru-Dark when dark mode is enabled from the Appearance setting.

When I create a gambas application using gb.gui or gb.gtk4 the resultant
application takes the dark theme. However when I use gb.gui.qt or gb.qt5
the resultant application doesn't take a dark theme. The reason I have to
stick to gb.qt5 is due to Textedit control in gb.gui.qt.ext and gb.qt5.ext.

How can I enable dark mode in gambas qt5 application in ubuntu?

[System]
Gambas=3.19.2
OperatingSystem=Linux
Distribution=Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Kernel=6.5.0-35-generic
Architecture=x86_64
Cores=4
Memory=3788M
Language=en_US.UTF-8
Platform=x11
Desktop=UBUNTU
DesktopResolution=96
DesktopScale=8
WidgetTheme=yaru-dark
Font=Ubuntu,11
[Programs]
dpkg=Debian 'dpkg' package management program version 1.21.1 (amd64).
gcc=gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0
msgmerge=msgmerge (GNU gettext-tools) 0.21
rpmbuild=RPM version 4.17.0
[Libraries]
Cairo=libcairo.so.2.11600.0
Curl=libcurl.so.4.7.0
DBus=libdbus-1.so.3.19.13
GDK2=libgdk-x11-2.0.so.0.2400.33
GDK3=libgdk-3.so.0.2404.29
GStreamer=libgstreamer-1.0.so.0.2003.0
GTK+2=libgtk-x11-2.0.so.0.2400.33
GTK+3=libgtk-3.so.0.2404.29
OpenGL=libGL.so.1.7.0
Poppler=libpoppler.so.118.0.0
QT5=libQt5Core.so.5.15.3
RSvg=librsvg-2.so.2.48.0
SDL=libSDL2-2.0.so.0.18.2
SQLite 3=libsqlite3.so.0.8.6
[Environment]
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
DESKTOP_SESSION=ubuntu-xorg
DISPLAY=:0
GB_GUI=gb.gtk3
GDMSESSION=ubuntu-xorg
GIO_LAUNCHED_DESKTOP_FILE=/usr/share/applications/gambas3.desktop
GIO_LAUNCHED_DESKTOP_FILE_PID=7503
GJS_DEBUG_OUTPUT=stderr
GJS_DEBUG_TOPICS=JS ERROR;JS LOG
GNOME_DESKTOP_SESSION_ID=this-is-deprecated
GNOME_SHELL_SESSION_MODE=ubuntu
GPG_AGENT_INFO=/run/user/1000/gnupg/S.gpg-agent:0:1
GTK_IM_MODULE=ibus
GTK_MODULES=gail:atk-bridge
HOME=<home>
INVOCATION_ID=8a65427b929f4bb699425e759f744764
JOURNAL_STREAM=8:31701
LANG=en_US.UTF-8
LC_ADDRESS=bho_NP
LC_ALL=en_US.UTF-8
LC_IDENTIFICATION=bho_NP
LC_MEASUREMENT=bho_NP
LC_MONETARY=bho_NP
LC_NAME=bho_NP
LC_NUMERIC=bho_NP
LC_PAPER=bho_NP
LC_TELEPHONE=bho_NP
LC_TIME=bho_NP
LOGNAME=<user>
MANAGERPID=1642
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/snap/bin
PWD=<home>
QT_ACCESSIBILITY=1
QT_IM_MODULE=ibus
QT_LOGGING_RULES=*.debug=false
SESSION_MANAGER=local/<hostname>:@/tmp/.ICE-unix/1875,unix/<hostname>:/tmp/.ICE-unix/1875
SHELL=/bin/bash
SHLVL=0
SSH_AGENT_LAUNCHER=gnome-keyring
SSH_AUTH_SOCK=/run/user/1000/keyring/ssh
SYSTEMD_EXEC_PID=1898
TZ=:/etc/localtime
USER=<user>
USERNAME=<user>
WINDOWPATH=2
XAUTHORITY=/run/user/1000/gdm/Xauthority
XDG_CONFIG_DIRS=/etc/xdg/xdg-ubuntu-xorg:/etc/xdg
XDG_CURRENT_DESKTOP=ubuntu:GNOME
XDG_DATA_DIRS=/usr/share/ubuntu-xorg:/usr/share/gnome:/usr/local/share/:/usr/share/:/var/lib/snapd/desktop
XDG_MENU_PREFIX=gnome-
XDG_RUNTIME_DIR=/run/user/1000
XDG_SESSION_CLASS=user
XDG_SESSION_DESKTOP=ubuntu-xorg
XDG_SESSION_TYPE=x11
XMODIFIERS=@im=ibus

-- 
Regards
Safiur Rahman