[gimp/wip/Jehan/issue-498-quick-brush-edit: 507/523] app: stop alt-right click brush size change when releasing Alt first.

[Jehan <jehanp src gnome org>]

commit e54f5cd13f36943c6ca34cfbd3e4a81da9a83a1b
Author: Jehan <jehan girinstud io>
Date:   Tue Feb 15 12:18:42 2022 +0100

    app: stop alt-right click brush size change when releasing Alt first.
    
    Until now, it was only stopiing when releasing right click, but it's
    actually more accurate when releasing the Alt key first as the button is
    on the mouse/stylus (so releasing it can provoke small hand moves,
    especially visible with stylus, I think). Now it stops whatever is
    released first.

 app/display/gimpdisplayshell-tool-events.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)
---
diff --git a/app/display/gimpdisplayshell-tool-events.c b/app/display/gimpdisplayshell-tool-events.c
index 4d1f205d2c..eeb31b2861 100644
--- a/app/display/gimpdisplayshell-tool-events.c
+++ b/app/display/gimpdisplayshell-tool-events.c
@@ -541,7 +541,6 @@ gimp_display_shell_canvas_tool_events (GtkWidget        *canvas,
               }
             else if (mod_state == GDK_MOD1_MASK)
               {
-                shell->mod1_settings = TRUE;
                 gimp_display_shell_start_scrolling (shell, event, state,
                                                     bevent->x, bevent->y);
               }
@@ -1099,15 +1098,21 @@ gimp_display_shell_canvas_tool_events (GtkWidget        *canvas,
 
         active_tool = tool_manager_get_active (gimp);
 
-        if (gimp_display_shell_key_to_state (kevent->keyval) == GDK_MOD1_MASK &&
-            shell->picked_layer)
+        if (gimp_display_shell_key_to_state (kevent->keyval) == GDK_MOD1_MASK)
           {
-            GimpStatusbar *statusbar;
+            if (shell->picked_layer)
+              {
+                GimpStatusbar *statusbar;
 
-            statusbar = gimp_display_shell_get_statusbar (shell);
-            gimp_statusbar_pop_temp (statusbar);
+                statusbar = gimp_display_shell_get_statusbar (shell);
+                gimp_statusbar_pop_temp (statusbar);
 
-            shell->picked_layer = NULL;
+                shell->picked_layer = NULL;
+              }
+            else if (shell->mod1_settings)
+              {
+                gimp_display_shell_stop_scrolling (shell, event);
+              }
           }
 
         if ((state & GDK_BUTTON1_MASK)      &&