IsItemHovered() comments (#1382)

imgui.cpp

@@ -2026,26 +2026,35 @@ bool ImGui::ItemAdd(const ImRect& bb, ImGuiID id)
 bool ImGui::IsItemHovered(ImGuiHoveredFlags flags)
 {
     ImGuiContext& g = *GImGui;
-
     ImGuiWindow* window = g.CurrentWindow;
+
+    // Test for bounding box overlap, as updated as ItemAdd()
     if (!window->DC.LastItemRectHoveredRect)
         return false;
     IM_ASSERT((flags & ImGuiHoveredFlags_FlattenChilds) == 0);   // Flags not supported by this function
 
+    // Test if we are hovering the right window (our window could be behind another window)
     // [2017/10/16] Reverted commit 344d48be3 and testing RootWindow instead. I believe it is correct to NOT test for RootWindow but this leaves us unable to use IsItemHovered() after EndChild() itself.
     // Until a solution is found I believe reverting to the test from 2017/09/27 is safe since this was the test that has been running for a long while.
     //if (g.HoveredWindow != window)
     //    return false;
     if (g.HoveredRootWindow != window->RootWindow && !(flags & ImGuiHoveredFlags_AllowWhenOverlapped))
         return false;
+
+    // Test if another item is active (e.g. being dragged)
     if (!(flags & ImGuiHoveredFlags_AllowWhenBlockedByActiveItem))
         if (g.ActiveId != 0 && g.ActiveId != window->DC.LastItemId && !g.ActiveIdAllowOverlap && g.ActiveId != window->MoveId)
             return false;
+
+    // Test if interactions on this window are blocked by an active popup or modal 
     if (!IsWindowContentHoverable(window, flags))
         return false;
+
+    // Test if the item is disabled
     if (window->DC.ItemFlags & ImGuiItemFlags_Disabled)
         return false;
-    // Special handling for the 1st item after Begin() which represent the title bar. When the window is collapsed (SkipItems==true) that last item will never be overwritten.
+    
+    // Special handling for the 1st item after Begin() which represent the title bar. When the window is collapsed (SkipItems==true) that last item will never be overwritten so we need to detect tht case.
     if (window->DC.LastItemId == window->MoveId && window->WriteAccessed)
         return false;
     return true;