BeginPopupContextItem() now supports a NULL string identifier and uses the last item ID if available. For interactive items (that have an ID) this works! For non interactive items we assert.

imgui.cpp

@@ -3697,38 +3697,43 @@ void ImGui::EndPopup()
         PopStyleVar();
 }
 
-// This is a helper to handle the most simple case of associating one named popup to one given widget.
+// This is a helper to handle the simplest case of associating one named popup to one given widget.
 // 1. If you have many possible popups (for different "instances" of a same widget, or for wholly different widgets), you may be better off handling
 //    this yourself so you can store data relative to the widget that opened the popup instead of choosing different popup identifiers.
 // 2. If you want right-clicking on the same item to reopen the popup at new location, use the same code replacing IsItemHovered() with IsItemRectHovered()
 //    and passing true to the OpenPopupEx().
-//    Because: hovering an item in a window below the popup won't normally trigger is hovering behavior/coloring. The pattern of ignoring the fact that
-//    the item can be interacted with (because it is blocked by the active popup) may useful in some situation when e.g. large canvas as one item, content of menu
-//    driven by click position.
+//    This is because hovering an item in a window below the popup won't work. IsItemRectHovered() skips this test.
+//    The pattern of ignoring the fact that the item can be interacted with (because it is blocked by the active popup) may useful in some situation 
+//    when e.g. large canvas where the content of menu driven by click position.
 bool ImGui::BeginPopupContextItem(const char* str_id, int mouse_button)
 {
+    ImGuiWindow* window = GImGui->CurrentWindow;
+    ImGuiID id = str_id ? window->GetID(str_id) : window->DC.LastItemId; // If user hasn't passed an ID, we can use the LastItemID. Using LastItemID as a Popup ID won't conflict!
+    IM_ASSERT(id != 0);                                                  // However, you cannot pass a NULL str_id if the last item has no identifier (e.g. a Text() item)
     if (IsItemHovered() && IsMouseClicked(mouse_button))
-        OpenPopupEx(GImGui->CurrentWindow->GetID(str_id), false);
-    return BeginPopup(str_id);
+        OpenPopupEx(id, false);
+    return BeginPopupEx(id, 0);
 }
 
 bool ImGui::BeginPopupContextWindow(const char* str_id, int mouse_button, bool also_over_items)
 {
     if (!str_id)
         str_id = "window_context";
+    ImGuiID id = GImGui->CurrentWindow->GetID(str_id);
     if (IsWindowRectHovered() && IsMouseClicked(mouse_button))
         if (also_over_items || !IsAnyItemHovered())
-            OpenPopupEx(GImGui->CurrentWindow->GetID(str_id), true);
-    return BeginPopup(str_id);
+            OpenPopupEx(id, true);
+    return BeginPopupEx(id, 0);
 }
 
 bool ImGui::BeginPopupContextVoid(const char* str_id, int mouse_button)
 {
     if (!str_id) 
         str_id = "void_context";
+    ImGuiID id = GImGui->CurrentWindow->GetID(str_id);
     if (!IsAnyWindowHovered() && IsMouseClicked(mouse_button))
-        OpenPopupEx(GImGui->CurrentWindow->GetID(str_id), true);
-    return BeginPopup(str_id);
+        OpenPopupEx(id, true);
+    return BeginPopupEx(id, 0);
 }
 
 static bool BeginChildEx(const char* name, ImGuiID id, const ImVec2& size_arg, bool border, ImGuiWindowFlags extra_flags)

imgui.h

@@ -392,7 +392,7 @@ namespace ImGui
     IMGUI_API void          OpenPopup(const char* str_id);                                      // call to mark popup as open (don't call every frame!). popups are closed when user click outside, or if CloseCurrentPopup() is called within a BeginPopup()/EndPopup() block. By default, Selectable()/MenuItem() are calling CloseCurrentPopup(). Popup identifiers are relative to the current ID-stack (so OpenPopup and BeginPopup needs to be at the same level).
     IMGUI_API bool          BeginPopup(const char* str_id);                                     // return true if the popup is open, and you can start outputting to it. only call EndPopup() if BeginPopup() returned true!
     IMGUI_API bool          BeginPopupModal(const char* name, bool* p_open = NULL, ImGuiWindowFlags extra_flags = 0);               // modal dialog (block interactions behind the modal window, can't close the modal window by clicking outside)
-    IMGUI_API bool          BeginPopupContextItem(const char* str_id, int mouse_button = 1);                                        // helper to open and begin popup when clicked on last item. read comments in .cpp!
+    IMGUI_API bool          BeginPopupContextItem(const char* str_id = NULL, int mouse_button = 1);                                 // helper to open and begin popup when clicked on last item. if you can pass a NULL str_id only if the previous item had an id. If you want to use that on a non-interactive item such as Text() you need to pass in an explicit ID here. read comments in .cpp!
     IMGUI_API bool          BeginPopupContextWindow(const char* str_id = NULL, int mouse_button = 1, bool also_over_items = true);  // helper to open and begin popup when clicked on current window.
     IMGUI_API bool          BeginPopupContextVoid(const char* str_id = NULL, int mouse_button = 1);                                 // helper to open and begin popup when clicked in void (no window).
     IMGUI_API void          EndPopup();

imgui_demo.cpp

@@ -1402,6 +1402,11 @@ void ImGui::ShowTestWindow(bool* p_open)
 
         if (ImGui::TreeNode("Context menus"))
         {
+            // BeginPopupContextItem() is a helper to provide common/simple popup behavior of essentially doing:
+            //    if (IsItemHovered() && IsMouseClicked(0))
+            //       OpenPopup(id);
+            //    return BeginPopup(id);
+            // For more advanced uses you may want to replicate and cuztomize this code. This the comments inside BeginPopupContextItem() implementation.
             static float value = 0.5f;
             ImGui::Text("Value = %.3f (<-- right-click here)", value);
             if (ImGui::BeginPopupContextItem("item context menu"))
@@ -1413,9 +1418,9 @@ void ImGui::ShowTestWindow(bool* p_open)
             }
 
             static char name[32] = "Label1";
-            char buf[64]; sprintf(buf, "Button: %s###Button", name); // ### operator override ID ignoring the preceeding label
+            char buf[64]; sprintf(buf, "Button: %s###Button", name); // ### operator override ID ignoring the preceding label
             ImGui::Button(buf);
-            if (ImGui::BeginPopupContextItem("rename context menu"))
+            if (ImGui::BeginPopupContextItem()) // When used after an item that has an ID (here the Button), we can skip providing an ID to BeginPopupContextItem().
             {
                 ImGui::Text("Edit name:");
                 ImGui::InputText("##edit", name, IM_ARRAYSIZE(name));