Inputs: SetItemKeyOwner(): return true if ownership has been requested, which can to be checked to accurately gate further input test.

(#456, #2637, #2620, #2891, #3370, #3724, #4828, #5108, #5242, #5641)

imgui.h

@@ -1092,10 +1092,11 @@ namespace ImGui
     // Inputs Utilities: Key/Input Ownership [BETA]
     // - One common use case would be to allow your items to disable standard inputs behaviors such
     //   as Tab or Alt key handling, Mouse Wheel scrolling, etc.
-    //   e.g. Button(...); SetItemKeyOwner(ImGuiKey_MouseWheelY); to make hovering/activating a button disable wheel for scrolling.
+    //   e.g. `Button(...); if (SetItemKeyOwner(ImGuiKey_MouseWheelY)) { ... }` to make hovering/activating a button disable wheel for scrolling.
     // - Reminder ImGuiKey enum include access to mouse buttons and gamepad, so key ownership can apply to them.
+    // - The return value of SetItemKeyOwner() says if ownership has been requested for the item, which is a shortcut to calling yet non-public TestKeyOwner() function.
     // - Many related features are still in imgui_internal.h. For instance, most IsKeyXXX()/IsMouseXXX() functions have an owner-id-aware version.
-    IMGUI_API void          SetItemKeyOwner(ImGuiKey key);                                      // Set key owner to last item ID if it is hovered or active. Equivalent to 'if (IsItemHovered() || IsItemActive()) { SetKeyOwner(key, GetItemID());'.
+    IMGUI_API bool          SetItemKeyOwner(ImGuiKey key);                                      // Set key owner to last item ID if it is hovered or active. Return true when ownership has been set. Roughly equivalent to 'if (TestKeyOwner(key, GetItemID()) && (IsItemHovered() || IsItemActive())) { SetKeyOwner(key, GetItemID());'. 
 
     // Inputs Utilities: Mouse
     // - To refer to a mouse button, you may use named enums in your code e.g. ImGuiMouseButton_Left, ImGuiMouseButton_Right.