Platform: expose also modifier keys in KeyEvent::Key enum.

Was done for GLFW but not for SDL2. Also updated the docs to reflect the
connection between them.

src/Magnum/Platform/GlfwApplication.h

@@ -500,10 +500,33 @@ class GlfwApplication::InputEvent {
          *      @ref MouseEvent::modifiers()
          */
         enum class Modifier: Int {
-            Shift = GLFW_MOD_SHIFT,         /**< Shift */
-            Ctrl = GLFW_MOD_CONTROL,        /**< Ctrl */
-            Alt = GLFW_MOD_ALT,             /**< Alt */
-            Super = GLFW_MOD_SUPER          /**< Super key (Windows/⌘) */
+            /**
+             * Shift
+             *
+             * @see @ref KeyEvent::Key::LeftShift, @ref KeyEvent::Key::RightShift
+             */
+            Shift = GLFW_MOD_SHIFT,
+
+            /**
+             * Ctrl
+             *
+             * @see @ref KeyEvent::Key::LeftCtrl, @ref KeyEvent::Key::RightCtrl
+             */
+            Ctrl = GLFW_MOD_CONTROL,
+
+            /**
+             * Alt
+             *
+             * @see @ref KeyEvent::Key::LeftAlt, @ref KeyEvent::Key::RightAlt
+             */
+            Alt = GLFW_MOD_ALT,
+
+            /**
+             * Super key (Windows/⌘)
+             *
+             * @see @ref KeyEvent::Key::LeftSuper, @ref KeyEvent::Key::RightSuper
+             */
+            Super = GLFW_MOD_SUPER
         };
 
         /**
@@ -560,6 +583,62 @@ class GlfwApplication::KeyEvent: public GlfwApplication::InputEvent {
         enum class Key: Int {
             Unknown = GLFW_KEY_UNKNOWN,         /**< Unknown key */
 
+            /**
+             * Left Shift
+             *
+             * @see @ref InputEvent::Modifier::Shift
+             */
+            LeftShift = GLFW_KEY_LEFT_SHIFT,
+
+            /**
+             * Right Shift
+             *
+             * @see @ref InputEvent::Modifier::Shift
+             */
+            RightShift = GLFW_KEY_RIGHT_SHIFT,
+
+            /**
+             * Left Ctrl
+             *
+             * @see @ref InputEvent::Modifier::Ctrl
+             */
+            LeftCtrl = GLFW_KEY_LEFT_CONTROL,
+
+            /**
+             * Right Ctrl
+             *
+             * @see @ref InputEvent::Modifier::Ctrl
+             */
+            RightCtrl = GLFW_KEY_RIGHT_CONTROL,
+
+            /**
+             * Left Alt
+             *
+             * @see @ref InputEvent::Modifier::Alt
+             */
+            LeftAlt = GLFW_KEY_LEFT_ALT,
+
+            /**
+             * Right Alt
+             *
+             * @see @ref InputEvent::Modifier::Alt
+             */
+            RightAlt = GLFW_KEY_RIGHT_ALT,
+
+            /**
+             * Left Super key (Windows/⌘)
+             *
+             * @see @ref InputEvent::Modifier::Super
+             */
+            LeftSuper = GLFW_KEY_LEFT_SUPER,
+
+            /**
+             * Right Super key (Windows/⌘)
+             *
+             * @see @ref InputEvent::Modifier::Super
+             */
+            RightSuper = GLFW_KEY_RIGHT_SUPER,
+
             Enter = GLFW_KEY_ENTER,             /**< Enter */
             Esc = GLFW_KEY_ESCAPE,              /**< Escape */
 
@@ -662,14 +741,6 @@ class GlfwApplication::KeyEvent: public GlfwApplication::InputEvent {
             NumAdd = GLFW_KEY_KP_ADD,           /**< Numpad add */
             NumEnter = GLFW_KEY_KP_ENTER,       /**< Numpad enter */
             NumEqual = GLFW_KEY_KP_EQUAL,       /**< Numpad equal */
-            LeftShift = GLFW_KEY_LEFT_SHIFT,    /**< Left shift */
-            LeftCtrl = GLFW_KEY_LEFT_CONTROL,   /**< Left control */
-            LeftAlt = GLFW_KEY_LEFT_ALT,        /**< Left alt */
-            LeftSuper = GLFW_KEY_LEFT_SUPER,    /**< Left super */
-            RightShift = GLFW_KEY_RIGHT_SHIFT,  /**< Right shift */
-            RightCtrl = GLFW_KEY_RIGHT_CONTROL, /**< Right control */
-            RightAlt = GLFW_KEY_RIGHT_ALT,      /**< Right alt */
-            RightSuper = GLFW_KEY_RIGHT_SUPER,  /**< Right super */
             Menu = GLFW_KEY_MENU                /**< Menu */
         };
 

src/Magnum/Platform/Sdl2Application.h

@@ -971,11 +971,40 @@ class Sdl2Application::InputEvent {
          *      @ref MouseEvent::modifiers(), @ref MouseMoveEvent::modifiers()
          */
         enum class Modifier: Uint16 {
-            Shift = KMOD_SHIFT,         /**< Shift */
-            Ctrl = KMOD_CTRL,           /**< Ctrl */
-            Alt = KMOD_ALT,             /**< Alt */
-            Super = KMOD_GUI,           /**< Super key (Windows/⌘) */
-            AltGr = KMOD_MODE,          /**< AltGr */
+            /**
+             * Shift
+             *
+             * @see @ref KeyEvent::Key::LeftShift, @ref KeyEvent::Key::RightShift
+             */
+            Shift = KMOD_SHIFT,
+
+            /**
+             * Ctrl
+             *
+             * @see @ref KeyEvent::Key::LeftCtrl, @ref KeyEvent::Key::RightCtrl
+             */
+            Ctrl = KMOD_CTRL,
+
+            /**
+             * Alt
+             *
+             * @see @ref KeyEvent::Key::LeftAlt, @ref KeyEvent::Key::RightAlt
+             */
+            Alt = KMOD_ALT,
+
+            /**
+             * Super key (Windows/⌘)
+             *
+             * @see @ref KeyEvent::Key::LeftSuper, @ref KeyEvent::Key::RightSuper
+             */
+            Super = KMOD_GUI,
+
+            /**
+             * AltGr
+             *
+             * @see @ref KeyEvent::Key::AltGr
+             */
+            AltGr = KMOD_MODE,
 
             CapsLock = KMOD_CAPS,       /**< Caps lock */
             NumLock = KMOD_NUM          /**< Num lock */
@@ -1042,6 +1071,69 @@ class Sdl2Application::KeyEvent: public Sdl2Application::InputEvent {
         enum class Key: SDL_Keycode {
             Unknown = SDLK_UNKNOWN,     /**< Unknown key */
 
+            /**
+             * Left Shift
+             *
+             * @see @ref InputEvent::Modifier::Shift
+             */
+            LeftShift = SDLK_LSHIFT,
+
+            /**
+             * Right Shift
+             *
+             * @see @ref InputEvent::Modifier::Shift
+             */
+            RightShift = SDLK_RSHIFT,
+
+            /**
+             * Left Ctrl
+             *
+             * @see @ref InputEvent::Modifier::Ctrl
+             */
+            LeftCtrl = SDLK_LCTRL,
+
+            /**
+             * Right Ctrl
+             *
+             * @see @ref InputEvent::Modifier::Ctrl
+             */
+            RightCtrl = SDLK_RCTRL,
+
+            /**
+             * Left Alt
+             *
+             * @see @ref InputEvent::Modifier::Alt
+             */
+            LeftAlt = SDLK_LALT,
+
+            /**
+             * Right Alt
+             *
+             * @see @ref InputEvent::Modifier::Alt
+             */
+            RightAlt = SDLK_RALT,
+
+            /**
+             * Left Super key (Windows/⌘)
+             *
+             * @see @ref InputEvent::Modifier::Super
+             */
+            LeftSuper = SDLK_LGUI,
+
+            /**
+             * Right Super key (Windows/⌘)
+             *
+             * @see @ref InputEvent::Modifier::Super
+             */
+            RightSuper = SDLK_RGUI,
+
+            /**
+             * AltGr
+             *
+             * @see @ref InputEvent::Modifier::AltGr
+             */
+            AltGr = SDLK_MODE,
+
             Enter = SDLK_RETURN,        /**< Enter */
             Esc = SDLK_ESCAPE,          /**< Escape */