chore: mouse events are overrided only if windows were pinned (#4)

This allows move multiple windows by dragging only one of them.

Author: ostenemes

Sources/SpringMotionPanel.swift

@@ -66,15 +66,15 @@ public extension SpringMotionPanel {
     override func mouseDown(with event: NSEvent) {
         super.mouseDown(with: event)
         // Stop window from moving if the user grabbed it.
-        if isMovableByWindowBackground {
+        if isMovableByWindowBackground, anchorWindowFrameObservation != nil {
             stopMotion()
         }
     }
 
     override func mouseUp(with event: NSEvent) {
         super.mouseUp(with: event)
         // Continue movement after the user lets go.
-        if isMovableByWindowBackground {
+        if isMovableByWindowBackground, anchorWindowFrameObservation != nil {
             startMotion()
         }
     }

Sources/SpringMotionWindow.swift

@@ -66,15 +66,15 @@ extension SpringMotionWindow {
     override open func mouseDown(with event: NSEvent) {
         super.mouseDown(with: event)
         // Stop window from moving if the user grabbed it.
-        if isMovableByWindowBackground {
+        if isMovableByWindowBackground, anchorWindowFrameObservation != nil {
             stopMotion()
         }
     }
 
     override open func mouseUp(with event: NSEvent) {
         super.mouseUp(with: event)
         // Continue movement after the user lets go.
-        if isMovableByWindowBackground {
+        if isMovableByWindowBackground, anchorWindowFrameObservation != nil {
             startMotion()
         }
     }