TabItem: honor ImGuiTabItemFlags_NoCloseButton passed as parameter (although undocumented and part of private api) (#2923)

imgui_demo.cpp

@@ -2027,7 +2027,7 @@ static void ShowDemoWindowLayout()
             if (ImGui::BeginTabBar("MyTabBar", tab_bar_flags))
             {
                 for (int n = 0; n < IM_ARRAYSIZE(opened); n++)
-                    if (opened[n] && ImGui::BeginTabItem(names[n], &opened[n]))
+                    if (opened[n] && ImGui::BeginTabItem(names[n], &opened[n], ImGuiTabItemFlags_None))
                     {
                         ImGui::Text("This is the %s tab!", names[n]);
                         if (n & 1)

imgui_internal.h

@@ -1512,7 +1512,7 @@ enum ImGuiTabBarFlagsPrivate_
 // Extend ImGuiTabItemFlags_
 enum ImGuiTabItemFlagsPrivate_
 {
-    ImGuiTabItemFlags_NoCloseButton             = 1 << 20   // Store whether p_open is set or not, which we need to recompute ContentWidth during layout.
+    ImGuiTabItemFlags_NoCloseButton             = 1 << 20   // Track whether p_open was set or not (we'll need this info on the next frame to recompute ContentWidth during layout)
 };
 
 // Storage for one active tab item (sizeof() 26~32 bytes)

imgui_widgets.cpp

@@ -6927,6 +6927,12 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
         return false;
     }
 
+    // Store into ImGuiTabItemFlags_NoCloseButton, also honor ImGuiTabItemFlags_NoCloseButton passed by user (although not documented)
+    if (flags & ImGuiTabItemFlags_NoCloseButton)
+        p_open = NULL;
+    else if (p_open == NULL)
+        flags |= ImGuiTabItemFlags_NoCloseButton;
+
     // Calculate tab contents size
     ImVec2 size = TabItemCalcSize(label, p_open != NULL);
 
@@ -6944,9 +6950,6 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
     tab_bar->LastTabItemIdx = (short)tab_bar->Tabs.index_from_ptr(tab);
     tab->ContentWidth = size.x;
 
-    if (p_open == NULL)
-        flags |= ImGuiTabItemFlags_NoCloseButton;
-
     const bool tab_bar_appearing = (tab_bar->PrevFrameVisible + 1 < g.FrameCount);
     const bool tab_bar_focused = (tab_bar->Flags & ImGuiTabBarFlags_IsFocused) != 0;
     const bool tab_appearing = (tab->LastFrameVisible + 1 < g.FrameCount);