Style: minor menubar bg alpha tweak.

imgui.cpp

@@ -391,7 +391,6 @@
  - window: resizing from any sides? + mouse cursor directives for app.
  - window: get size/pos helpers given names (see discussion in #249)
  - window: a collapsed window can be stuck behind the main menu bar?
- - scrolling: add horizontal scroll
 !- scrolling: allow immediately effective change of scroll if we haven't appended items yet
  - widgets: display mode: widget-label, label-widget (aligned on column or using fixed size), label-newline-tab-widget etc.
  - widgets: clean up widgets internal toward exposing everything.
@@ -638,7 +637,7 @@ ImGuiStyle::ImGuiStyle()
     Colors[ImGuiCol_TitleBg]                = ImVec4(0.50f, 0.50f, 1.00f, 0.45f);
     Colors[ImGuiCol_TitleBgCollapsed]       = ImVec4(0.40f, 0.40f, 0.80f, 0.20f);
     Colors[ImGuiCol_TitleBgActive]          = ImVec4(0.50f, 0.50f, 1.00f, 0.55f);
-    Colors[ImGuiCol_MenuBarBg]              = ImVec4(0.40f, 0.40f, 0.55f, 0.60f);
+    Colors[ImGuiCol_MenuBarBg]              = ImVec4(0.40f, 0.40f, 0.55f, 0.80f);
     Colors[ImGuiCol_ScrollbarBg]            = ImVec4(0.40f, 0.40f, 0.80f, 0.15f);
     Colors[ImGuiCol_ScrollbarGrab]          = ImVec4(0.40f, 0.40f, 0.80f, 0.30f);
     Colors[ImGuiCol_ScrollbarGrabHovered]   = ImVec4(0.40f, 0.40f, 0.80f, 0.40f);