PR# 18544 {EV_APPLICATION}.process events does not work properly in finalized app

I have a data save/load progress dialog which displays a pixmap and then draws some patterns over it to indicate the progress. It works consistently well from within EStudio but in my finalized app the pixmap (more often than not) fails to display and also the first trigram pattern. However logging output indicates that the draw_pixmap call was made, so why didn't it display?

Relevant code is below.

As a workaround I can put the serialization operation in a separate thread. But for the sake of simplicity it would be nice if process_events worked.


feature -- Element change

   set_progress (proportion: DOUBLE)
      local
         next_trigram_index: INTEGER
      do
         if is_displayed then
            next_trigram_index := (trigram_index_upper * (proportion.min (1.0))).rounded
            if next_trigram_index > trigram_interval.upper then
               trigram_interval.resize_exactly (trigram_interval.upper + 1, next_trigram_index)
               redraw
               GUI.application.process_events
            end
         end
      end

feature -- Status query

   is_pixmap_displayed: BOOLEAN

feature {NONE} -- Implementation

   on_redraw (a_x, a_y, a_width, a_height: INTEGER)
      do
         log.enter ("on_redraw")
         if not is_pixmap_displayed then
            draw_pixmap (0, 0, Pixmaps.waterfall_pixmap)
            log.put_line ("draw_pixmap")
            is_pixmap_displayed := True
         end
         across trigram_interval as trigram_index loop
            move_trigram_outer_area (trigram_index.item)
            draw_trigram
         end
         log.exit
      end

Have you tried clear_and_redraw instead of just redraw, this will first clear the drawing area to the default background color first.  The following code sample works:

class
	APPLICATION

inherit
	EV_APPLICATION

create
	make_and_launch

feature {NONE} -- Initialization

	make_and_launch
			-- Initialize and launch application
		do
			default_create
			prepare
			launch
		end

	prepare
		local
			l_da: EV_DRAWING_AREA
			l_vb: EV_VERTICAL_BOX
			l_but: EV_BUTTON
		do
				-- create and initialize the first window.
			create first_window

			create l_da
			l_da.expose_actions.extend (agent on_redraw (l_da, ?, ?, ?, ?))

			create l_vb

			create l_but.make_with_text ("Click Me")

			l_but.select_actions.force_extend (agent handle_click (l_da))

			l_vb.extend (l_da)
			l_vb.extend (l_but)

			first_window.extend (l_vb)

				-- Show the first window.
				--| TODO: Remove this line if you don't want the first
				--|       window to be shown at the start of the progr
....
Output truncated, Click download to get the full message

PS I have exhaustively tried various things to try and get the initial drawings to appear, calling flush immediately after redraw for example, or calling  process events both before and after. I have also tried process_graphical_events in various combinations with the others and alone.

None of them make any difference to the problem.

I even tried using a pixmap instead of a EV_DRAWABLE_AREA but for some strange reason all the colors went to monochrome.