refactored window storage;

new helper window events (Destroyed, Created);
clippy + fmt;

core/src/window/settings/windows.rs

@@ -0,0 +1,21 @@
+//! Platform specific settings for Windows.
+use raw_window_handle::RawWindowHandle;
+
+/// The platform specific window settings of an application.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct PlatformSpecific {
+    /// Parent window
+    pub parent: Option<RawWindowHandle>,
+
+    /// Drag and drop support
+    pub drag_and_drop: bool,
+}
+
+impl Default for PlatformSpecific {
+    fn default() -> Self {
+        Self {
+            parent: None,
+            drag_and_drop: true,
+        }
+    }
+}