Internals: Allow ItemHoverable() to be used with id==0 to facilitate high-level read-only hover test in widget code.

imgui.cpp

@@ -3172,6 +3172,10 @@ bool ImGui::ItemHoverable(const ImRect& bb, ImGuiID id)
     if (window->DC.ItemFlags & ImGuiItemFlags_Disabled)
         return false;
 
+    // We exceptionally allow this function to be called with id==0 to allow using it for easy high-level
+    // hover test in widgets code. We could also decide to split this function is two.
+    if (id != 0)
+    {
         SetHoveredID(id);
 
         // [DEBUG] Item Picker tool!
@@ -3183,6 +3187,7 @@ bool ImGui::ItemHoverable(const ImRect& bb, ImGuiID id)
             GetForegroundDrawList()->AddRect(bb.Min, bb.Max, IM_COL32(255, 255, 0, 255));
         if (g.DebugItemPickerBreakId == id)
             IM_DEBUG_BREAK();
+    }
 
     return true;
 }