Style: Allow style.WindowMenuButtonPosition to be set to ImGuiDir_None to hide the collapse button. (#2634, #2639)

+ Fix #2775

docs/CHANGELOG.txt

@@ -50,6 +50,7 @@ Other Changes:
 - SliderScalar: Improved assert when using U32 or U64 types with a large v_max value. (#2765) [@loicmouton]
 - DragInt, DragFloat, DragScalar: Using (v_min > v_max) allows locking any edit to the value.
 - DragScalar: Fixed dragging of unsigned values on ARM cpu. (#2780) [@dBagrat]
+- Style: Allow style.WindowMenuButtonPosition to be set to ImGuiDir_None to hide the collapse button. (#2634, #2639)
 - Font: Better ellipsis drawing implementation. Instead of drawing three pixel-ey dots (which was glaringly
   unfitting with many types of fonts) we first attempt to find a standard ellipsis glyphs within the loaded set.
   Otherwise we render ellipsis using '.' from the font from where we trim excessive spacing to make it as narrow

imgui.cpp

@@ -3692,7 +3692,7 @@ static void NewFrameSanityChecks()
     IM_ASSERT(g.Style.CurveTessellationTol > 0.0f                       && "Invalid style setting!");
     IM_ASSERT(g.Style.Alpha >= 0.0f && g.Style.Alpha <= 1.0f            && "Invalid style setting. Alpha cannot be negative (allows us to avoid a few clamps in color computations)!");
     IM_ASSERT(g.Style.WindowMinSize.x >= 1.0f && g.Style.WindowMinSize.y >= 1.0f && "Invalid style setting.");
-    IM_ASSERT(g.Style.WindowMenuButtonPosition == ImGuiDir_Left || g.Style.WindowMenuButtonPosition == ImGuiDir_Right);
+    IM_ASSERT(g.Style.WindowMenuButtonPosition == ImGuiDir_None || g.Style.WindowMenuButtonPosition == ImGuiDir_Left || g.Style.WindowMenuButtonPosition == ImGuiDir_Right);
     for (int n = 0; n < ImGuiKey_COUNT; n++)
         IM_ASSERT(g.IO.KeyMap[n] >= -1 && g.IO.KeyMap[n] < IM_ARRAYSIZE(g.IO.KeysDown) && "io.KeyMap[] contains an out of bound value (need to be 0..512, or -1 for unmapped key)");
 
@@ -5314,7 +5314,7 @@ void ImGui::RenderWindowTitleBarContents(ImGuiWindow* window, const ImRect& titl
     ImGuiWindowFlags flags = window->Flags;
 
     const bool has_close_button = (p_open != NULL);
-    const bool has_collapse_button = !(flags & ImGuiWindowFlags_NoCollapse);
+    const bool has_collapse_button = !(flags & ImGuiWindowFlags_NoCollapse) && (style.WindowMenuButtonPosition != ImGuiDir_None);
 
     // Close & Collapse button are on the Menu NavLayer and don't default focus (unless there's nothing else on that layer)
     const ImGuiItemFlags item_flags_backup = window->DC.ItemFlags;

imgui.h

@@ -1289,7 +1289,7 @@ struct ImGuiStyle
     float       WindowBorderSize;           // Thickness of border around windows. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly).
     ImVec2      WindowMinSize;              // Minimum window size. This is a global setting. If you want to constraint individual windows, use SetNextWindowSizeConstraints().
     ImVec2      WindowTitleAlign;           // Alignment for title bar text. Defaults to (0.0f,0.5f) for left-aligned,vertically centered.
-    ImGuiDir    WindowMenuButtonPosition;   // Side of the collapsing/docking button in the title bar (left/right). Defaults to ImGuiDir_Left.
+    ImGuiDir    WindowMenuButtonPosition;   // Side of the collapsing/docking button in the title bar (None/Left/Right). Defaults to ImGuiDir_Left.
     float       ChildRounding;              // Radius of child window corners rounding. Set to 0.0f to have rectangular windows.
     float       ChildBorderSize;            // Thickness of border around child windows. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly).
     float       PopupRounding;              // Radius of popup window corners rounding. (Note that tooltip windows use WindowRounding)

imgui_demo.cpp

@@ -3195,7 +3195,9 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
             ImGui::SliderFloat("TabRounding", &style.TabRounding, 0.0f, 12.0f, "%.0f");
             ImGui::Text("Alignment");
             ImGui::SliderFloat2("WindowTitleAlign", (float*)&style.WindowTitleAlign, 0.0f, 1.0f, "%.2f");
-            ImGui::Combo("WindowMenuButtonPosition", (int*)&style.WindowMenuButtonPosition, "Left\0Right\0");
+            int window_menu_button_position = style.WindowMenuButtonPosition + 1;
+            if (ImGui::Combo("WindowMenuButtonPosition", (int*)&window_menu_button_position, "None\0Left\0Right\0"))
+                style.WindowMenuButtonPosition = window_menu_button_position - 1;
             ImGui::Combo("ColorButtonPosition", (int*)&style.ColorButtonPosition, "Left\0Right\0");
             ImGui::SliderFloat2("ButtonTextAlign", (float*)&style.ButtonTextAlign, 0.0f, 1.0f, "%.2f"); ImGui::SameLine(); HelpMarker("Alignment applies when a button is larger than its text content.");
             ImGui::SliderFloat2("SelectableTextAlign", (float*)&style.SelectableTextAlign, 0.0f, 1.0f, "%.2f"); ImGui::SameLine(); HelpMarker("Alignment applies when a selectable is larger than its text content.");
@@ -3284,7 +3286,7 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
                     ImGui::InputFloat("Font offset", &font->DisplayOffset.y, 1, 1, "%.0f");
                     ImGui::Text("Ascent: %f, Descent: %f, Height: %f", font->Ascent, font->Descent, font->Ascent - font->Descent);
                     ImGui::Text("Fallback character: '%c' (U+%04X)", font->FallbackChar, font->FallbackChar);
-                    ImGui::Text("Ellipsis character: '%c' (U+%04X)", font->EllipsisChar);
+                    ImGui::Text("Ellipsis character: '%c' (U+%04X)", font->EllipsisChar, font->EllipsisChar);
                     const float surface_sqrt = sqrtf((float)font->MetricsTotalSurface);
                     ImGui::Text("Texture surface: %d pixels (approx) ~ %dx%d", font->MetricsTotalSurface, (int)surface_sqrt, (int)surface_sqrt);
                     for (int config_i = 0; config_i < font->ConfigDataCount; config_i++)