Update conditionals and formatting

src/OpenTK/Platform/MacOS/CocoaNativeWindow.cs

@@ -1236,21 +1236,19 @@ namespace OpenTK.Platform.MacOS
 
         public override bool CursorVisible
         {
-            get { return cursorVisible; }
+            get
+            {
+                return cursorVisible;
+            }
             set
             {
-                if (value == cursorVisible) return;
+                if (value != cursorVisible)
-                if (value && !cursorVisible)
                 {
-                    SetCursorVisible(true);
+                    SetCursorVisible(value);
-                }
-                else if (!value && cursorVisible)
-                {
-                    SetCursorVisible(false);
-                }
                     cursorVisible = value;
                 }
             }
+        }
 
         protected override void Dispose(bool disposing)
         {

src/OpenTK/Platform/SDL2/Sdl2NativeWindow.cs

@@ -933,10 +933,9 @@ namespace OpenTK.Platform.SDL2
             }
             set
             {
-                if (value == is_cursor_visible) return;
                 lock (sync)
                 {
-                    if (Exists)
+                    if (Exists && value != is_cursor_visible)
                     {
                         GrabCursor(!value);
                         is_cursor_visible = value;

src/OpenTK/Platform/Windows/WinGLNative.cs

@@ -1256,10 +1256,17 @@ namespace OpenTK.Platform.Windows
 
         public override bool CursorVisible
         {
-            get { return cursor_visible_count >= 0; }
+            get
+            {
+                return cursor_visible_count >= 0;
+            }
             set
             {
-                if (value && cursor_visible_count < 0)
+                if (value == CursorVisible)
+                {
+                    return;
+                }
+                if (value)
                 {
                     do
                     {
@@ -1269,7 +1276,7 @@ namespace OpenTK.Platform.Windows
 
                     UngrabCursor();
                 }
-                else if (!value && cursor_visible_count >= 0)
+                else
                 {
                     do
                     {

src/OpenTK/Platform/X11/X11GLNative.cs

@@ -1684,12 +1684,19 @@ namespace OpenTK.Platform.X11
 
         public override bool CursorVisible
         {
-            get { return cursor_visible; }
+            get
+            {
+                return cursor_visible;
+            }
             set
             {
-                if (value && !cursor_visible)
+                if (value == cursor_visible)
                 {
+                    return;
+                }
                 using (new XLock(window.Display))
+                {
+                    if (value)
                     {
                         UngrabMouse();
 
@@ -1699,16 +1706,12 @@ namespace OpenTK.Platform.X11
                         // Note: if cursorHandle = IntPtr.Zero, this restores the default cursor
                         // (equivalent to calling XUndefineCursor)
                         Functions.XDefineCursor(window.Display, window.Handle, cursorHandle);
-                        cursor_visible = true;
                     }
-                }
+                    else
-                else if (!value && cursor_visible)
-                {
-                    using (new XLock(window.Display))
                     {
                         GrabMouse();
-                        cursor_visible = false;
                     }
+                    cursor_visible = value;
                 }
             }
         }