Hicolor needs to be set as fallback

[konsolebox]

qBittorrent & operating system versions

qBittorrent: 4.5.4
Operating system: Gentoo
Qt: 5.15.10

What is the problem?

qBittorrent should set 'hicolor' as fallback if it's going to install its icons in it otherwise it will have an implied dependency on an icon theme that inherits hicolor being set. It should explicitly make sure its icons are being used.

These are the icon files in qbittorrent-4.5.4_lt20_x86_64.AppImage:

./usr/share/icons/hicolor/192x192/status/qbittorrent-tray.png
./usr/share/icons/hicolor/192x192/apps/qbittorrent.png
./usr/share/icons/hicolor/24x24/status/qbittorrent-tray.png
./usr/share/icons/hicolor/24x24/apps/qbittorrent.png
./usr/share/icons/hicolor/32x32/status/qbittorrent-tray.png
./usr/share/icons/hicolor/32x32/apps/qbittorrent.png
./usr/share/icons/hicolor/64x64/status/qbittorrent-tray.png
./usr/share/icons/hicolor/64x64/apps/qbittorrent.png
./usr/share/icons/hicolor/48x48/status/qbittorrent-tray.png
./usr/share/icons/hicolor/48x48/apps/qbittorrent.png
./usr/share/icons/hicolor/96x96/status/qbittorrent-tray.png
./usr/share/icons/hicolor/96x96/apps/qbittorrent.png
./usr/share/icons/hicolor/16x16/status/qbittorrent-tray.png
./usr/share/icons/hicolor/16x16/apps/qbittorrent.png
./usr/share/icons/hicolor/72x72/status/qbittorrent-tray.png
./usr/share/icons/hicolor/72x72/apps/qbittorrent.png
./usr/share/icons/hicolor/128x128/status/qbittorrent-tray.png
./usr/share/icons/hicolor/128x128/apps/qbittorrent.png
./usr/share/icons/hicolor/36x36/status/qbittorrent-tray.png
./usr/share/icons/hicolor/36x36/apps/qbittorrent.png
./usr/share/icons/hicolor/22x22/status/qbittorrent-tray.png
./usr/share/icons/hicolor/22x22/apps/qbittorrent.png

This is the patch I used for 4.5.4 but it won't work with main/master.

diff --git a/src/gui/uithememanager.cpp b/src/gui/uithememanager.cpp
index 25412eb..77cd935 100644
--- a/src/gui/uithememanager.cpp
+++ b/src/gui/uithememanager.cpp
@@ -245,6 +245,7 @@ QColor UIThemeManager::getColor(const QString &id, const QColor &defaultColor) c
 QIcon UIThemeManager::getSystrayIcon() const
 {
     const TrayIcon::Style style = Preferences::instance()->trayIconStyle();
+    QIcon::setFallbackSearchPaths(QIcon::fallbackSearchPaths() << QString::fromUtf8("/usr/share/icons/hicolor"));
     switch (style)
     {
 #if defined(Q_OS_UNIX)

Steps to reproduce

Keep system's icon theme unset or theoretically set it to an icon theme that doesn't inherit hicolor.

Additional context

https://bugs.gentoo.org/911542

Log(s) & preferences file(s)

No response