Feature request (patch included): add ImGuiTabBarFlags_X option to remove separator line under tab-bar

[nobody-special666]

Version: latest
Branch: docking

Back-ends: any
Compiler: any
Operating System: any

This is a follow-up to my previous issue #4850.
Attached is a patch to prevent the separator line under the tab-bar from being drawn in case the user doesn't want it.
And also adds the option to the imgui_demo.

Please consider for inclusion.
Thanks for ImGui!
Regards.

diff --git a/imgui.h b/imgui.h
index ceb3b086d..ace89ebc1 100644
--- a/imgui.h
+++ b/imgui.h
@@ -1144,6 +1144,7 @@ enum ImGuiTabBarFlags_
     ImGuiTabBarFlags_NoTooltip                      = 1 << 5,   // Disable tooltips when hovering a tab
     ImGuiTabBarFlags_FittingPolicyResizeDown        = 1 << 6,   // Resize tabs when they don't fit
     ImGuiTabBarFlags_FittingPolicyScroll            = 1 << 7,   // Add scroll buttons when tabs don't fit
+    ImGuiTabBarFlags_NoBaseSeparator                = 1 << 8,   // Disable drawing the separator line at the base of tabs
     ImGuiTabBarFlags_FittingPolicyMask_             = ImGuiTabBarFlags_FittingPolicyResizeDown | ImGuiTabBarFlags_FittingPolicyScroll,
     ImGuiTabBarFlags_FittingPolicyDefault_          = ImGuiTabBarFlags_FittingPolicyResizeDown
 };
diff --git a/imgui_demo.cpp b/imgui_demo.cpp
index 5d6779e9a..24b4c6e30 100644
--- a/imgui_demo.cpp
+++ b/imgui_demo.cpp
@@ -1592,6 +1592,7 @@ static void ShowDemoWindowWidgets()
                 tab_bar_flags &= ~(ImGuiTabBarFlags_FittingPolicyMask_ ^ ImGuiTabBarFlags_FittingPolicyResizeDown);
             if (ImGui::CheckboxFlags("ImGuiTabBarFlags_FittingPolicyScroll", &tab_bar_flags, ImGuiTabBarFlags_FittingPolicyScroll))
                 tab_bar_flags &= ~(ImGuiTabBarFlags_FittingPolicyMask_ ^ ImGuiTabBarFlags_FittingPolicyScroll);
+            ImGui::CheckboxFlags("ImGuiTabBarFlags_NoBaseSeparator", &tab_bar_flags, ImGuiTabBarFlags_NoBaseSeparator);
 
             // Tab Bar
             const char* names[4] = { "Artichoke", "Beetroot", "Celery", "Daikon" };
@@ -1644,6 +1645,7 @@ static void ShowDemoWindowWidgets()
                 tab_bar_flags &= ~(ImGuiTabBarFlags_FittingPolicyMask_ ^ ImGuiTabBarFlags_FittingPolicyResizeDown);
             if (ImGui::CheckboxFlags("ImGuiTabBarFlags_FittingPolicyScroll", &tab_bar_flags, ImGuiTabBarFlags_FittingPolicyScroll))
                 tab_bar_flags &= ~(ImGuiTabBarFlags_FittingPolicyMask_ ^ ImGuiTabBarFlags_FittingPolicyScroll);
+            ImGui::CheckboxFlags("ImGuiTabBarFlags_NoBaseSeparator", &tab_bar_flags, ImGuiTabBarFlags_NoBaseSeparator);
 
             if (ImGui::BeginTabBar("MyTabBar", tab_bar_flags))
             {
diff --git a/imgui_widgets.cpp b/imgui_widgets.cpp
index 89e3681e4..213b26632 100644
--- a/imgui_widgets.cpp
+++ b/imgui_widgets.cpp
@@ -7333,20 +7333,24 @@ bool    ImGui::BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& tab_bar_bb, ImG
     window->DC.CursorPos = ImVec2(tab_bar->BarRect.Min.x, tab_bar->BarRect.Max.y + tab_bar->ItemSpacingY);
 
     // Draw separator
-    const ImU32 col = GetColorU32((flags & ImGuiTabBarFlags_IsFocused) ? ImGuiCol_TabActive : ImGuiCol_TabUnfocusedActive);
-    const float y = tab_bar->BarRect.Max.y - 1.0f;
-    if (dock_node != NULL)
+    if ((flags & ImGuiTabBarFlags_NoBaseSeparator) == 0)
     {
-        const float separator_min_x = dock_node->Pos.x + window->WindowBorderSize;
-        const float separator_max_x = dock_node->Pos.x + dock_node->Size.x - window->WindowBorderSize;
-        window->DrawList->AddLine(ImVec2(separator_min_x, y), ImVec2(separator_max_x, y), col, 1.0f);
-    }
-    else
-    {
-        const float separator_min_x = tab_bar->BarRect.Min.x - IM_FLOOR(window->WindowPadding.x * 0.5f);
-        const float separator_max_x = tab_bar->BarRect.Max.x + IM_FLOOR(window->WindowPadding.x * 0.5f);
-        window->DrawList->AddLine(ImVec2(separator_min_x, y), ImVec2(separator_max_x, y), col, 1.0f);
+        const ImU32 col = GetColorU32((flags & ImGuiTabBarFlags_IsFocused) ? ImGuiCol_TabActive : ImGuiCol_TabUnfocusedActive);
+        const float y = tab_bar->BarRect.Max.y - 1.0f;
+        if (dock_node != NULL)
+        {
+            const float separator_min_x = dock_node->Pos.x + window->WindowBorderSize;
+            const float separator_max_x = dock_node->Pos.x + dock_node->Size.x - window->WindowBorderSize;
+            window->DrawList->AddLine(ImVec2(separator_min_x, y), ImVec2(separator_max_x, y), col, 1.0f);
+        }
+        else
+        {
+            const float separator_min_x = tab_bar->BarRect.Min.x - IM_FLOOR(window->WindowPadding.x * 0.5f);
+            const float separator_max_x = tab_bar->BarRect.Max.x + IM_FLOOR(window->WindowPadding.x * 0.5f);
+            window->DrawList->AddLine(ImVec2(separator_min_x, y), ImVec2(separator_max_x, y), col, 1.0f);
+        }
     }
+
     return true;
 }

[ocornut]

You can surround BeginTabBar() with a PushStyleColor/PopStyleColor() call to make those colors 0 then restore it to render tabs?

[nobody-special666]

Thanks for quick response.
I did not know about PushStyleColor().
You are correct, closing ticket.

ImGui::PushStyleColor(ImGuiCol_TabActive, IM_COL32(0,0,0,0));
ImGui::PushStyleColor(ImGuiCol_TabUnfocusedActive, IM_COL32(0,0,0,0));

bool bTabBar= ImGui::BeginTabBar("MyTabBar", tab_bar_flags);

ImGui::PopStyleColor();
ImGui::PopStyleColor();

[ocornut]

FYI
Now added a style.TabBarBorderSize variable,
So ImGui::PushStyleVar(ImGuiStyleVar_TabBarBorderSize, 0.0f) will also work.