I am uploading a NMU to DELAYED/10 in order fix this.
The debdiff is attached.
diff -Nru transgui-5.18.0+dfsg/debian/changelog
transgui-5.18.0+dfsg/debian/changelog
--- transgui-5.18.0+dfsg/debian/changelog 2022-05-08 22:41:20.000000000
+0200
+++ transgui-5.18.0+dfsg/debian/changelog 2023-09-20 12:07:04.000000000
+0200
@@ -1,3 +1,11 @@
+transgui (5.18.0+dfsg-3.1) unstable; urgency=medium
+
+ * Non-maintainer upload
+ * Build with widgetset qt5 (Closes: #967782)
+ * Drop Build-Depends: libgdk-pixbuf2.0-dev (Closes: #1037404)
+
+ -- Bastian Germann <b...@debian.org> Wed, 20 Sep 2023 12:07:04 +0200
+
transgui (5.18.0+dfsg-3) unstable; urgency=medium
* Re-add libssl-dev dependency (LP: #1971896)
diff -Nru transgui-5.18.0+dfsg/debian/control
transgui-5.18.0+dfsg/debian/control
--- transgui-5.18.0+dfsg/debian/control 2022-05-08 22:41:20.000000000 +0200
+++ transgui-5.18.0+dfsg/debian/control 2023-09-20 12:07:04.000000000 +0200
@@ -7,14 +7,10 @@
fp-utils,
fpc,
imagemagick,
- lcl-gtk2,
+ lcl-qt5,
lcl-units,
lcl-utils,
- libatk1.0-dev,
libcairo2-dev,
- libgdk-pixbuf2.0-dev,
- libgtk2.0-dev,
- libpango1.0-dev,
libssl-dev,
libx11-dev
Standards-Version: 4.6.0
diff -Nru transgui-5.18.0+dfsg/debian/patches/build-with-qt5-widgetset.patch
transgui-5.18.0+dfsg/debian/patches/build-with-qt5-widgetset.patch
--- transgui-5.18.0+dfsg/debian/patches/build-with-qt5-widgetset.patch
1970-01-01 01:00:00.000000000 +0100
+++ transgui-5.18.0+dfsg/debian/patches/build-with-qt5-widgetset.patch
2023-09-20 12:07:04.000000000 +0200
@@ -0,0 +1,21 @@
+From: Bastian Germann <b...@debian.org>
+Date: Wed, 20 Sep 2023 12:44:29 +0200
+Subject: Build with qt5 widgetset
+
+---
+ Makefile.fpc | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/Makefile.fpc b/Makefile.fpc
+index 4622c4d..6ff3e1e 100644
+--- a/Makefile.fpc
++++ b/Makefile.fpc
+@@ -32,7 +32,7 @@ $(info Using Lazarus dir: $(LAZARUS_DIR))
+ LAZRES=$(LAZARUS_DIR)/tools/lazres$(SRCEXEEXT)
+
+ # Widgetset
+-LCL_WIDGETSET=gtk2
++LCL_WIDGETSET=qt5
+ ifneq ($(findstring $(OS_TARGET),win32,win64),)
+ LCL_WIDGETSET=win32
+ endif
diff -Nru transgui-5.18.0+dfsg/debian/patches/series
transgui-5.18.0+dfsg/debian/patches/series
--- transgui-5.18.0+dfsg/debian/patches/series 2022-05-08 22:41:20.000000000
+0200
+++ transgui-5.18.0+dfsg/debian/patches/series 2023-09-20 12:07:04.000000000
+0200
@@ -2,3 +2,4 @@
#fix.open.patch
#force_ssl1.0.2.patch
patch_connect_transmission_3.0
+build-with-qt5-widgetset.patch