fix: use selected window for /clearmessages (#5489)

CHANGELOG.md

@@ -25,6 +25,7 @@
 - Bugfix: Fixed message history occasionally not loading after a sleep. (#5457)
 - Bugfix: Fixed a crash when tab completing while having an invalid plugin loaded. (#5401)
 - Bugfix: Fixed windows on Windows not saving correctly when snapping them to the edges. (#5478)
+- Bugfix: Fixed `/clearmessages` not working with more than one window. (#5489)
 - Dev: Update Windows build from Qt 6.5.0 to Qt 6.7.1. (#5420)
 - Dev: Update vcpkg build Qt from 6.5.0 to 6.7.0, boost from 1.83.0 to 1.85.0, openssl from 3.1.3 to 3.3.0. (#5422)
 - Dev: Unsingletonize `ISoundController`. (#5462)

src/controllers/commands/builtin/Misc.cpp

@@ -401,11 +401,11 @@ QString clearmessages(const CommandContext &ctx)
 {
     (void)ctx;
 
-    auto *currentPage = dynamic_cast<SplitContainer *>(getIApp()
-                                                           ->getWindows()
-                                                           ->getMainWindow()
-                                                           .getNotebook()
-                                                           .getSelectedPage());
+    auto *currentPage = getIApp()
+                            ->getWindows()
+                            ->getLastSelectedWindow()
+                            ->getNotebook()
+                            .getSelectedPage();
 
     if (auto *split = currentPage->getSelectedSplit())
     {