Scrollbar: background color less translucent in default style (flattened alpha) so it works better on non-WindowBg colored background.

imgui.cpp

@@ -665,7 +665,7 @@ ImGuiStyle::ImGuiStyle()
     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, 0.80f);
-    Colors[ImGuiCol_ScrollbarBg]            = ImVec4(0.40f, 0.40f, 0.80f, 0.15f);
+    Colors[ImGuiCol_ScrollbarBg]            = ImVec4(0.20f, 0.25f, 0.30f, 0.60f);
     Colors[ImGuiCol_ScrollbarGrab]          = ImVec4(0.40f, 0.40f, 0.80f, 0.30f);
     Colors[ImGuiCol_ScrollbarGrabHovered]   = ImVec4(0.40f, 0.40f, 0.80f, 0.40f);
     Colors[ImGuiCol_ScrollbarGrabActive]    = ImVec4(0.80f, 0.50f, 0.50f, 0.40f);