On linux/wayland demoShow doesn't immediatly show window

[Jaap Aarts]

I am running praat on linux/wayland, and need to run some scripts which makes use of the demo functionality (see script below). However only at the end does the demo window get shown. This is of course not the intended way it should be displayed.

I did some debugging, and the c function Demo_show does not immediatly show the window, it seems to only be drawn when gtk goes into an idle state.

If there is any more information you need/want, let me know.

form The necessity to window signal parts.
  comment Displays sequential short-term spectra of artificial vowel sound.
  positive Window_length_(msec) 25
  real Overlap_part_of_window_(%) 50
  choice Window 1
  button Rectangular
  button Hanning
endform

dur = 0.3
Create Sound from formula: "base", 1, 0, dur, 44100, "0"
To Pitch: 0, 75, 600
Down to PitchTier
Add point: 0, 125
To Sound (pulse train): 44100, 1, 0.05, 2000, "no"
Filter (one formant): 420, 60
Filter (one formant): 1400, 80

# Omit start effect.
Extract part: 0.02, 0.3, "rectangular", 1, "no"

Rename... vowel

win = window_length/1000
tStep = win*(1-overlap_part_of_window/100)

if tStep<(win/50)
  exit Choose lower overlap part.
endif


steps = floor(dur/tStep)
for i to steps-1
  select Sound vowel
  t1 = (i-1)*tStep
  t2 = t1+win
  Extract part: t1, t2, "rectangular", 1, "no"
  if window = 2
    Multiply by window: "Hanning"
  endif

  demo Erase all
  demo Select outer viewport: 0, 50, 25, 75
  demo Draw: 0, 0, -1, 1, "yes"

  To Spectrum (dft)
  demo Select outer viewport: 50, 100, 25, 75
  demo Draw: 0, 5000, 0, 0, "yes"
  if i < steps-1
    demo Select inner viewport: 20, 80, 20, 80
    demo Text top: "yes", "Still busy.."
  endif
  demoShow()
  plus Sound vowel_part
  Remove
  sleep (0.9)
endfor

demo Select inner viewport: 20, 80, 20, 80
if window = 1
  demo Text top: "yes", "Now you may start over, choosing Hanning window."
else
  demo Text top: "yes", "Now you may start over, choosing Rectangular window."
endif