Improve highlighting structure

- switched to a sparse delta based map
- true lazy-loading to avoid any unneccessary allocations
- fixed windows management api

src/ui/bar.cc

@@ -10,7 +10,8 @@ void Bar::log(std::string message) { log_line = message; }
 void Bar::render(std::vector<ScreenCell> &buffer) {
   USING(LSPInstance);
   BarLine bar_line;
-  bar_line = bar_contents(mode, screen.col, pwd.string(), focused_window);
+  bar_line =
+      bar_contents(mode, screen.col, pwd.string(), layout::focused_window);
   auto update = [&](uint32_t row, uint32_t col, std::string text, uint32_t fg,
                     uint32_t bg, uint8_t flags, uint32_t width) {
     ScreenCell &c = buffer[row * screen.col + col];
@@ -61,8 +62,8 @@ void Bar::handle_command(std::string &command) {
     running = false;
     return;
   }
-  if (focused_window)
-    focused_window->handle_command(command);
+  if (layout::focused_window)
+    layout::focused_window->handle_command(command);
 }
 
 void Bar::handle_event(KeyEvent event) {