fix: don't attempt to scale windows opted out of scaling (#5400)

CHANGELOG.md

@@ -8,7 +8,7 @@
 - Minor: Colored usernames now update on the fly when changing the "Color @usernames" setting. (#5300)
 - Minor: Added `flags.action` filter variable, allowing you to filter on `/me` messages. (#5397)
 - Bugfix: If a network request errors with 200 OK, Qt's error code is now reported instead of the HTTP status. (#5378)
-- Dev: Use Qt's high DPI scaling. (#4868)
+- Dev: Use Qt's high DPI scaling. (#4868, #5400)
 - Dev: Add doxygen build target. (#5377)
 - Dev: Make printing of strings in tests easier. (#5379)
 - Dev: Refactor and document `Scrollbar`. (#5334, #5393)

src/widgets/BaseWindow.cpp

@@ -931,9 +931,27 @@ void BaseWindow::updateScale()
 
     this->setScale(scale);
 
-    for (auto *child : this->findChildren<BaseWidget *>())
+    BaseWindow::applyScaleRecursive(this, scale);
+}
+
+// NOLINTNEXTLINE(misc-no-recursion)
+void BaseWindow::applyScaleRecursive(QObject *root, float scale)
+{
+    for (QObject *obj : root->children())
     {
-        child->setScale(scale);
+        auto *base = dynamic_cast<BaseWidget *>(obj);
+        if (base)
+        {
+            auto *window = dynamic_cast<BaseWindow *>(obj);
+            if (window)
+            {
+                // stop here, the window will get the event as well (via uiScale)
+                continue;
+            }
+            base->setScale(scale);
+        }
+
+        applyScaleRecursive(obj, scale);
     }
 }
 

src/widgets/BaseWindow.hpp

@@ -131,6 +131,8 @@ private:
     void drawCustomWindowFrame(QPainter &painter);
     void onFocusLost();
 
+    static void applyScaleRecursive(QObject *root, float scale);
+
     bool handleSHOWWINDOW(MSG *msg);
     bool handleSIZE(MSG *msg);
     bool handleMOVE(MSG *msg);

src/widgets/dialogs/SettingsDialog.cpp

@@ -196,7 +196,7 @@ void SettingsDialog::filterElements(const QString &text)
         auto *item = this->ui_.tabContainer->itemAt(i);
         if (auto *x = dynamic_cast<QSpacerItem *>(item); x)
         {
-            x->changeSize(10, shouldShowSpace ? int(16 * this->scale()) : 0);
+            x->changeSize(10, shouldShowSpace ? 16 : 0);
             shouldShowSpace = false;
         }
         else if (item->widget())