appsMenu: Consider scale-factor in height computation

Actor heights are in physical pixels, while CSS measures are in logical
pixels, so we need to adjust accordingly to prevent the scale factor
from being applied twice.

https://gitlab.gnome.org/GNOME/gnome-shell-extensions/issues/102

extensions/apps-menu/extension.js

@@ -685,7 +685,10 @@ class ApplicationsButton extends PanelMenu.Button {
         //Load applications
         this._displayButtons(this._listApplications(null));
 
-        let height = this.categoriesBox.height + MENU_HEIGHT_OFFSET + 'px';
+        let themeContext = St.ThemeContext.get_for_stage(global.stage);
+        let scaleFactor = themeContext.scale_factor;
+        let categoriesHeight = this.categoriesBox.height / scaleFactor;
+        let height = Math.round(categoriesHeight) + MENU_HEIGHT_OFFSET + 'px';
         this.mainBox.style+=('height: ' + height);
     }