Update CHANGELOG-v3.50.md

Author: photonstorm

CHANGELOG-v3.50.md

@@ -629,7 +629,8 @@ Since v3.0.0 the Game Object `render` functions have received a parameter called
 * `Tween.seek` will no longer issue a console warning for `'Tween.seek duration too long'`, it's now up to you to check on the performance of tween seeking.
 * `WebGLRenderer.previousPipeline` is a new property that is set during a call to `clearPipeline` and used during calls to `rebindPipeline`, allowing the renderer to rebind any previous pipeline, not just the Multi Pipeline.
 * The `WebGLRenderer.rebindPipeline` method has been changed slightly. Previously, you had to specify the `pipelineInstance`, but this is now optional. If you don't, it will use the new `previousPipeline` property instead. If not set, or none given, it will now return without throwing gl errors as well.
-* If `inputWindowEvents` is set in the Game Config, then the `MouseManager` will now listen for the events on `window.top` instead of just `window`, which should help in situations where the pointer is released outside of an embedded iframe. Fix #4824 (thanks @rexrainbow)
+* If `inputWindowEvents` is set in the Game Config, then the `MouseManager` will now listen for the events on `window.top` instead of just `window`, which should help in situations where the pointer is released outside of an embedded iframe. This check is wrapped in a `try/catch` block, as not all sites allow access to `window.top` (specifically in cross-origin iframe situations) Fix #4824 (thanks @rexrainbow)
+* `MouseManager.isTop` is a new boolean read-only property that flags if the mouse event listeners were attached to `window.top` (true), or just `window` (false). By default Phaser will attempt `window.top`, but this isn't possible in all environments, such as cross-origin iframes, so it will fall back to `window` in those cases and set this property to false (thanks BunBunBun)
 * `Types.GameObjects.Text.GetTextSizeObject` is a new type def for the GetTextSize function results.
 * `Utils.Array.StableSort` has been recoded. It's now based on Two-Screens stable sort 0.1.8 and has been updated to fit into Phaser better and no longer create any window bound objects. The `inplace` function has been removed, just call `StableSort(array)` directly now. All classes that used `StableSort.inplace` have been updated to call it directly.
 * If a Scene is paused, or sent to sleep, it will automatically call `Keyboard.resetKeys`. This means that if you hold a key down, then sleep or pause a Scene, then release the key and resume or wake the Scene, it will no longer think it is still being held down (thanks @samme)