[fractal] sidebar: Fix oscillating scrollbar when hovered at the right place

[Julian Sparber <jsparber src gnome org>]

commit 99911c3fcfe820a92ff77a15e1be61bc35e71eaa
Author: Julian Sparber <julian sparber net>
Date:   Wed Sep 14 12:11:40 2022 +0200

    sidebar: Fix oscillating scrollbar when hovered at the right place
    
    This is a hack to fix this till the upstream bug is resolved.
    See: https://gitlab.gnome.org/GNOME/gtk/-/issues/4938
    
    Fixes: https://gitlab.gnome.org/GNOME/fractal/-/issues/925

 data/resources/ui/sidebar.ui | 2 +-
 src/session/sidebar/mod.rs   | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)
---
diff --git a/data/resources/ui/sidebar.ui b/data/resources/ui/sidebar.ui
index 2f3eb9b8f..69b31d73a 100644
--- a/data/resources/ui/sidebar.ui
+++ b/data/resources/ui/sidebar.ui
@@ -148,7 +148,7 @@
           </object>
         </child>
         <child>
-          <object class="GtkScrolledWindow">
+          <object class="GtkScrolledWindow" id="scrolled_window">
             <property name="vexpand">True</property>
             <property name="hscrollbar-policy">never</property>
             <property name="child">
diff --git a/src/session/sidebar/mod.rs b/src/session/sidebar/mod.rs
index 843951fc6..a32f4cacb 100644
--- a/src/session/sidebar/mod.rs
+++ b/src/session/sidebar/mod.rs
@@ -60,6 +60,8 @@ mod imp {
         #[template_child]
         pub headerbar: TemplateChild<adw::HeaderBar>,
         #[template_child]
+        pub scrolled_window: TemplateChild<gtk::ScrolledWindow>,
+        #[template_child]
         pub listview: TemplateChild<gtk::ListView>,
         #[template_child]
         pub room_search_entry: TemplateChild<gtk::SearchEntry>,
@@ -259,6 +261,13 @@ mod imp {
                     btn.set_popover(Some(account_switcher));
                 }
             }));
+
+            // FIXME: Remove this hack once https://gitlab.gnome.org/GNOME/gtk/-/issues/4938 is resolved
+            self.scrolled_window
+                .vscrollbar()
+                .first_child()
+                .unwrap()
+                .set_overflow(gtk::Overflow::Hidden);
         }
     }