fix: initial scrollbar behaviour in inactive tab (#5757)

Channel views could sometimes have their scrollbar be at the top instead
of bottom when they were first activated if it had messages in it

CHANGELOG.md

@@ -142,7 +142,7 @@
 - Dev: 7TV's `entitlement.reset` is now explicitly ignored. (#5685)
 - Dev: Qt 6.8 and later now default to the GDI fontengine. (#5710)
 - Dev: Moved to condition variables when shutting down worker threads. (#5721, #5733)
-- Dev: Reduced layouts in channel views when setting a channel. (#5737, #5748)
+- Dev: Reduced layouts in channel views when setting a channel. (#5737, #5748, #5757)
 
 ## 2.5.1
 

src/widgets/Scrollbar.hpp

@@ -179,7 +179,7 @@ private:
 
     boost::circular_buffer<ScrollbarHighlight> highlights_;
 
-    bool atBottom_{false};
+    bool atBottom_{true};
     bool hideThumb{false};
     /// Controlled by the "Hide scrollbar thumb" setting
     bool settingHideThumb{false};