From 75bbdf160b744d405af85f0209fac1ec2e3e6309 Mon Sep 17 00:00:00 2001
From: Arecsu <alejandro9r@gmail.com>
Date: Thu, 13 Aug 2026 13:43:53 -0300
Subject: [PATCH] fix: don't treat a relayed gesture cancel as a click in
 thumbtable/culling

The event-controller migration converted the thumbtable's
button-release-event signal to a GtkGestureMultiPress and inherited the
cancel->release bridge: on every gesture cancel the bridge fakes a
released(1,0,0), and the release handler interpreted that as a click.

A cancel is not a click: GTK3 cancels gestures on grab-notify/controller
resets, and a press whose release never arrived (e.g. the second press of
a double-click that switched to darkroom on press) keeps a stale point in
the gesture that a later hover crossing can cancel.  Moving the mouse
over the lighttable thumbtable then silently ran select_single() on the
hovered image (issue #21813).

Restore the pre-gesture semantics: the release handler only acts on a
real GDK button release -- exactly what the old button-release-event
handler received -- while the cancel->release relay stays for the
pressed-state cleanup the bauhaus handlers rely on.
---
 src/dtgtk/culling.c    | 11 +++++++++++
 src/dtgtk/thumbtable.c | 14 ++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/src/dtgtk/culling.c b/src/dtgtk/culling.c
index df01c3a407e..ce5b3a1e1b4 100644
--- a/src/dtgtk/culling.c
+++ b/src/dtgtk/culling.c
@@ -1061,6 +1061,17 @@ static void _event_button_release_cb(GtkGestureSingle *gesture,
 {
   table->panning = FALSE;
 
+  /* A gesture cancel is relayed to this handler so widgets can clean up
+   * their pressed state, but it is not a click (issue #21813).  Only a
+   * real GDK button release may toggle the culling selection. */
+  GdkEvent *release_event = gtk_get_current_event();
+  if(!release_event || release_event->type != GDK_BUTTON_RELEASE)
+  {
+    gdk_event_free(release_event);
+    return;
+  }
+  gdk_event_free(release_event);
+
   const dt_imgid_t overid = dt_control_get_mouse_over_id();
   // if the act_on algorithm need a specific culling "selection",
   // we use a very simple culling-specific selection
diff --git a/src/dtgtk/thumbtable.c b/src/dtgtk/thumbtable.c
index 9d042cb1ebf..54287eb1f6a 100644
--- a/src/dtgtk/thumbtable.c
+++ b/src/dtgtk/thumbtable.c
@@ -1621,6 +1621,20 @@ static void _event_button_release_cb(GtkGestureSingle *gesture,
      && cv != DT_VIEW_PRINT)
     return;
 
+  /* A gesture cancel is relayed to this handler so widgets can clean up
+   * their pressed state, but it is not a click: cancels can also fire for
+   * a long-dead press while merely hovering (issue #21813 -- the thumbtable
+   * re-selected the hovered image).  Only a real GDK button release may
+   * select/toggle, exactly like the pre-gesture button-release-event
+   * handler. */
+  GdkEvent *release_event = gtk_get_current_event();
+  if(!release_event || release_event->type != GDK_BUTTON_RELEASE)
+  {
+    gdk_event_free(release_event);
+    return;
+  }
+  gdk_event_free(release_event);
+
   dt_set_backthumb_time(0.0);
   const dt_imgid_t id = dt_control_get_mouse_over_id();