widgets/cliprect: use ShaderEffectSource to propagate mouse events

layer.effect causes warnings on reload for an unknown reason which
seems to be ownership or destruction time related. This commit uses
an alternate strategy to create the shader which does not show this
warning.

src/widgets/ClippingRectangle.qml

@@ -26,7 +26,7 @@ Item {
 	/// Defaults to true if any corner has a non-zero radius, otherwise false.
 	property /*bool*/alias antialiasing: rectangle.antialiasing
 	/// The background color of the rectangle, which goes under its content.
-	property color color: "white"
+	property /*color*/alias color: shader.backgroundColor
 	/// See @@QtQuick.Rectangle.border.
 	property clippingRectangleBorder border
 	/// Radius of all corners. Defaults to 0.
@@ -72,14 +72,21 @@ Item {
 			anchors.fill: parent
 			anchors.margins: root.contentInsideBorder ? root.border.width : 0
 		}
+	}
 
-		layer.enabled: true
-		layer.samplerName: "content"
-		layer.effect: ShaderEffect {
-			fragmentShader: `qrc:/Quickshell/Widgets/shaders/cliprect${root.contentUnderBorder ? "-ub" : ""}.frag.qsb`
-			property Rectangle rect: rectangle
-			property color backgroundColor: root.color
-			property color borderColor: root.border.color
-		}
+	ShaderEffectSource {
+		id: shaderSource
+		hideSource: true
+		sourceItem: contentItemContainer
+	}
+
+	ShaderEffect {
+		id: shader
+		anchors.fill: root
+		fragmentShader: `qrc:/Quickshell/Widgets/shaders/cliprect${root.contentUnderBorder ? "-ub" : ""}.frag.qsb`
+		property Rectangle rect: rectangle
+		property color backgroundColor: "white"
+		property color borderColor: root.border.color
+		property ShaderEffectSource content: shaderSource
 	}
 }