Improv Left Panel Layout with buttons on top

Seemed better to have large title for panel (Session, Playlist and Settings) and the selection buttons aligned int the top row. Minor adjustments of layout.

src/UserInterfaceManager.cpp

@@ -3399,7 +3399,7 @@ void Navigator::RenderSourcePannel(Source *s, const ImVec2 &iconsize)
         ImGui::Text("Source");
 
         // index indicator
-        ImGui::SetCursorPos(ImVec2(pannel_width_ - 2 * ImGui::GetTextLineHeight(), IMGUI_TOP_ALIGN));
+        ImGui::SetCursorPos(ImVec2(pannel_width_ - 2.8f * ImGui::GetTextLineHeightWithSpacing(), IMGUI_TOP_ALIGN));
         ImGui::TextDisabled("#%d", Mixer::manager().indexCurrentSource());
 
         ImGui::PopFont();
@@ -4612,8 +4612,6 @@ void Navigator::RenderMainPannelSession()
     //
     // Session
     //
-    ImGui::Text("Session");
-
     std::string sessions_current = Mixer::manager().session()->filename();
     if (sessions_current.empty())
         sessions_current = "<unsaved>";
@@ -4729,7 +4727,7 @@ void Navigator::RenderMainPannelSession()
                 ImGui::Text(" Custom thumbnail");
             }
             else {
-                ImGui::Text(" No thumbnail ");
+                ImGui::Text(" Automatic thumbnail ");
             }
             ImGui::EndTooltip();
         }
@@ -5080,8 +5078,6 @@ void Navigator::RenderMainPannelPlaylist()
     //
     // SESSION panel
     //
-    ImGui::Text("Playlists");
-
     // currently active playlist and folder
     static std::string playlist_header = PLAYLIST_FAVORITES;
     static Playlist active_playlist;
@@ -5571,20 +5567,7 @@ void Navigator::RenderMainPannelSettings()
     //
     // Appearance
     //
-    ImGui::Text("Settings");
-    ImGui::SameLine();
-    ImGui::SetCursorPosX( pannel_width_ IMGUI_RIGHT_ALIGN);
-    if ( ImGuiToolkit::IconButton(ICON_FA_SAVE,"Export settings\nYou can then "
-                                               "launch vimix with the option "
-                                               "'--settings filename.xml' "
-                                               "to restore output windows and configuration.") ){
-        // launch file dialog to select file to save settings
-        if (UserInterface::manager().settingsexportdialog)
-            UserInterface::manager().settingsexportdialog->open();
-    }
-
     int v = Settings::application.accent_color;
-    ImGui::Spacing();
     ImGui::SetCursorPosX(0.5f * width_);
     if (ImGui::RadioButton("##Color", &v, v)){
         Settings::application.accent_color = (v+1)%3;
@@ -5883,6 +5866,18 @@ void Navigator::RenderMainPannelSettings()
     //
     ImGuiToolkit::Spacing();
     ImGui::TextDisabled("System");
+    ImGui::SameLine();
+
+    ImGui::SetCursorPosX( pannel_width_ IMGUI_RIGHT_ALIGN);
+    if ( ImGuiToolkit::IconButton(ICON_FA_SAVE,"Export settings\nYou can then "
+                                               "launch vimix with the option "
+                                               "'--settings filename.xml' "
+                                               "to restore output windows and configuration.") ){
+        // launch file dialog to select file to save settings
+        if (UserInterface::manager().settingsexportdialog)
+            UserInterface::manager().settingsexportdialog->open();
+    }
+    ImGui::Spacing();
 
     static bool need_restart = false;
     static bool vsync = (Settings::application.render.vsync > 0);
@@ -6027,18 +6022,10 @@ void Navigator::RenderMainPannel(const ImVec2 &iconsize)
         // Temporary fix for preventing horizontal scrolling (https://github.com/ocornut/imgui/issues/2915)
         ImGui::SetScrollX(0);
 
-        //
-        // TITLE
-        //
-        ImGuiToolkit::PushFont(ImGuiToolkit::FONT_LARGE);
-        ImGui::SetCursorPosY(0.5f * (iconsize.y - ImGui::GetTextLineHeight()));
-        ImGui::Text("Vimix");
-
         //
         // Panel Mode selector
         //
-        //
-        ImGui::SetCursorPosY(width_ - style.WindowPadding.x);
+        ImGuiToolkit::PushFont(ImGuiToolkit::FONT_LARGE);
         ImGui::PushStyleVar(ImGuiStyleVar_SelectableTextAlign, ImVec2(0.5f, 0.5f));
         ImGui::Columns(5, NULL, false);
         bool selected_panel_mode[5] = {0};
@@ -6074,17 +6061,32 @@ void Navigator::RenderMainPannel(const ImVec2 &iconsize)
             ImGui::EndMenu();
         }
 
-        ImGui::SetCursorPosY(2.f * width_ - style.WindowPadding.x);
-
         //
         // Panel content
         //
-        if (pannel_main_mode_ == 0)
+        float __p = width_ + style.ItemSpacing.y + ImGui::GetTextLineHeightWithSpacing();
+        ImGui::SetCursorPosY(__p);
+        if (pannel_main_mode_ == 0) {
+            ImGuiToolkit::PushFont(ImGuiToolkit::FONT_LARGE);
+            ImGui::Text("Session");
+            ImGui::SetCursorPosY(__p + ImGui::GetFrameHeightWithSpacing());
+            ImGui::PopFont();
             RenderMainPannelSession();
-        else if (pannel_main_mode_ == 1)
+        }
+        else if (pannel_main_mode_ == 1) {
+            ImGuiToolkit::PushFont(ImGuiToolkit::FONT_LARGE);
+            ImGui::Text("Playlist");
+            ImGui::SetCursorPosY(__p + ImGui::GetFrameHeightWithSpacing());
+            ImGui::PopFont();
             RenderMainPannelPlaylist();
-        else
+        }
+        else {
+            ImGuiToolkit::PushFont(ImGuiToolkit::FONT_LARGE);
+            ImGui::Text("Settings");
+            ImGui::SetCursorPosY(__p + ImGui::GetFrameHeightWithSpacing());
+            ImGui::PopFont();
             RenderMainPannelSettings();
+        }
 
         //
         // About vimix