FIX: [ISXB-1733] Prevent the Add Control Scheme popup window from expanding beyond its parent's visible area (#2269)

Author: K-Tone

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -35,6 +35,7 @@ however, it has to be formatted properly to pass verification tests.
 - Fixed HID parsing not handling logical minimum and maximum values correctly when they are negative. This applies for platforms that parse HID descriptors in the package, e.g. macOS at the moment.
 - Fix usage of correct data format for stick axes in HID Layout Builder ([User contribution](https://github.com/Unity-Technologies/InputSystem/pull/2245))
 - Fixed InputSystemUIInputModule calling pointer events on parent objects even when the "Send Pointer Hover To Parent" is off on 2022.3.XX. This was  was previously only available on Unity 6 versions since 1.11.0. [ISXB-1296]
+- Limited the Add Control Scheme popup window max size to be its parent window, so that it won't resize beyond the visible area. [ISXB-1733](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1733)
 - Fixed an issue where the action icon would shrink or disappear from UI when an action has a very long name. [ISXB-1650](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1650).
 - Fixed upgrading input actions containing multiple processors [ISXB-1674](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1674).
 

Packages/com.unity.inputsystem/InputSystem/Editor/UITKAssetEditor/Views/ControlSchemesView.cs

@@ -57,7 +57,7 @@ public ControlSchemesView(VisualElement root, StateContainer stateContainer, boo
             var popupWindow = new PopupWindow
             {
                 text = "Add Control Scheme",
-                style = { position = new StyleEnum<Position>(Position.Absolute) }
+                style = { position = new StyleEnum<Position>(Position.Absolute), maxWidth = new StyleLength(new Length(100, LengthUnit.Percent)) }
             };
             popupWindow.contentContainer.Add(controlSchemeVisualElement);
             m_ModalWindow.Add(popupWindow);