Made setPresentationBackground save to run/update n times on AppKitBackend

Author: MiaKoring

Sources/AppKitBackend/AppKitBackend.swift

@@ -1736,10 +1736,17 @@ public final class AppKitBackend: AppBackend {
     }
 
     public func setPresentationBackground(of sheet: NSCustomSheet, to color: Color) {
+        if let backgroundView = sheet.backgroundView {
+            backgroundView.layer?.backgroundColor = color.nsColor.cgColor
+            return
+        }
+
         let backgroundView = NSView()
         backgroundView.wantsLayer = true
         backgroundView.layer?.backgroundColor = color.nsColor.cgColor
 
+        sheet.backgroundView = backgroundView
+
         if let existingContentView = sheet.contentView {
             let container = NSView()
             container.translatesAutoresizingMaskIntoConstraints = false
@@ -1777,6 +1784,8 @@ public final class NSCustomSheet: NSCustomWindow, NSWindowDelegate {
 
     public var interactiveDismissDisabled: Bool = false
 
+    public var backgroundView: NSView?
+
     public func dismiss() {
         onDismiss?()
         self.contentViewController?.dismiss(self)