factor out repaint to its own method

it's gotten complex enough to isolate it

frontend/ui/uimanager.lua

@@ -373,29 +373,8 @@ function UIManager:checkTasks()
     return wait_until
 end
 
--- this is the main loop of the UI controller
--- it is intended to manage input events and delegate
--- them to dialogs
-function UIManager:run()
-    self._running = true
-    while self._running do
-        local now = { util.gettime() }
-        local wait_until = self:checkTasks()
-
-        --DEBUG("---------------------------------------------------")
-        --DEBUG("exec stack", self._execution_stack)
-        --DEBUG("window stack", self._window_stack)
-        --DEBUG("dirty stack", self._dirty)
-        --DEBUG("---------------------------------------------------")
-
-        -- stop when we have no window to show
-        if #self._window_stack == 0 then
-            DEBUG("no dialog left to show")
-            self:quit()
-            return nil
-        end
-
-        -- repaint dirty widgets
+-- repaint dirty widgets
+function UIManager:repaint()
     local dirty = false
     local request_full_refresh = false
     local force_full_refresh = false
@@ -490,6 +469,29 @@ function UIManager:run()
         end
         self.update_regions_func = nil
     end
+end
+
+-- this is the main loop of the UI controller
+-- it is intended to manage input events and delegate
+-- them to dialogs
+function UIManager:run()
+    self._running = true
+    while self._running do
+        local now = { util.gettime() }
+        local wait_until = self:checkTasks()
+
+        --DEBUG("---------------------------------------------------")
+        --DEBUG("exec stack", self._execution_stack)
+        --DEBUG("window stack", self._window_stack)
+        --DEBUG("dirty stack", self._dirty)
+        --DEBUG("---------------------------------------------------")
+
+        -- stop when we have no window to show
+        if #self._window_stack == 0 then
+            DEBUG("no dialog left to show")
+            self:quit()
+            return nil
+        end
 
         self:checkTasks()