change font scale based on ui scale, fix brush outline color

src/app_layout.cpp

@@ -8,6 +8,7 @@
 #include "node_panel_floating.h"
 #include "settings.h"
 #include "serializer.h"
+#include "font.h"
 
 void App::title_update()
 {
@@ -935,10 +936,7 @@ void App::init_menu_tools()
 
                 ui_scale->on_select = [ui_scale](Node* target, int index)
                 {
-                    App::I->zoom = ui_scale->get_float(index);
-                    Settings::set("ui-scale", Serializer::Float(App::I->zoom));
-                    Settings::save();
-                    App::I->title_update();
+                    App::I->set_ui_scale(ui_scale->get_float(index));
                 };
             }
 
@@ -1420,6 +1418,15 @@ void App::initLayout()
     LOG("initializing layout completed");
 }
 
+void App::set_ui_scale(float scale)
+{
+    zoom = scale;
+    FontManager::change_scale(zoom * display_density);
+    Settings::set("ui-scale", Serializer::Float(zoom));
+    Settings::save();
+    App::I->title_update();
+}
+
 void App::set_ui_rtl(bool rtl)
 {
     ui_rtl = rtl;