Active widgets is not clipped, so it can always release its active state (mentioned in #143)

Otherwise a change in layout moving active widget to a clipped region
may lock the active id.

imgui.cpp

@@ -7264,10 +7264,13 @@ static bool ItemAdd(const ImRect& bb, const ImGuiID* id)
     window->DC.LastItemID = id ? *id : 0;
     window->DC.LastItemRect = bb;
     if (IsClipped(bb))
+    {
+        if (!id || *id != GImGui->ActiveId)
         {
             window->DC.LastItemHoveredAndUsable = window->DC.LastItemHoveredRect = false;
             return false;
         }
+    }
 
     // This is a sensible default, but widgets are free to override it after calling ItemAdd()
     ImGuiState& g = *GImGui;