scroll window on mouse wheel events

src/gui/BufferPane.cc

@@ -618,6 +618,7 @@ void BufferPane::scroll_window_up()
         move_cursor_screen_row_up();
     }
     m_cursor_screen_row += lines_to_scroll;
+    m_window->request_redraw();
 }
 
 void BufferPane::scroll_window_down()
@@ -630,6 +631,7 @@ void BufferPane::scroll_window_down()
         move_cursor_screen_row_down();
     }
     m_cursor_screen_row -= lines_to_scroll;
+    m_window->request_redraw();
 }
 
 void BufferPane::forward_to_column(int column, bool allow_eol)

src/gui/Window.cc

@@ -216,6 +216,17 @@ void Window::handle_event(SDL_Event & event)
     case SDL_USEREVENT:
         handle_keysym((uint32_t)(uintptr_t)event.user.data1);
         break;
+
+    case SDL_MOUSEWHEEL:
+        if (event.wheel.y > 0)
+        {
+            m_buffer_pane->scroll_window_up();
+        }
+        else
+        {
+            m_buffer_pane->scroll_window_down();
+        }
+        break;
     }
 }