GUI: Give MouseEvent shift() / ctrl() / alt() / logo() functions

Author: https://github.com/nico
Commit: https://github.com/SerenityOS/serenity/commit/cb2d56b9096
Pull-request: https://github.com/SerenityOS/serenity/pull/3102

Libraries/LibGUI/Event.h

@@ -331,6 +331,10 @@ public:
     int y() const { return m_position.y(); }
     MouseButton button() const { return m_button; }
     unsigned buttons() const { return m_buttons; }
+    bool ctrl() const { return m_modifiers & Mod_Ctrl; }
+    bool alt() const { return m_modifiers & Mod_Alt; }
+    bool shift() const { return m_modifiers & Mod_Shift; }
+    bool logo() const { return m_modifiers & Mod_Logo; }
     unsigned modifiers() const { return m_modifiers; }
     int wheel_delta() const { return m_wheel_delta; }
 

Libraries/LibGUI/ScrollableWidget.cpp

@@ -61,7 +61,7 @@ void ScrollableWidget::mousewheel_event(MouseEvent& event)
         return;
     }
     // FIXME: The wheel delta multiplier should probably come from... somewhere?
-    if (event.modifiers() & Mod_Shift) {
+    if (event.shift()) {
         horizontal_scrollbar().set_value(horizontal_scrollbar().value() + event.wheel_delta() * 60);
     } else {
         vertical_scrollbar().set_value(vertical_scrollbar().value() + event.wheel_delta() * 20);