drawing code called excessively frequently

[vtjnash]

source annotation indicates that reveal(::Canvas) gets called 3 times per resize event (on Mac OS X, if relevant)

[JeffBezanson]

Is the resize event paired with an expose event? It may be that some platforms give both events in this case.

[vtjnash]

Here's the backtraces upon entry to the reveal function:
(note: I have reverted b6be415 on my local copy)

 function reveal(c::Canvas)
+    println("reveal: ")
+    Base.show_backtrace(STDOUT,backtrace())

julia> plot(1:100)
reveal: 
 in reveal at /Users/jameson/.julia/Tk/src/tkwidget.jl:322
 in draw at /Users/jameson/.julia/Tk/src/tkwidget.jl:268
 in configure at /Users/jameson/.julia/Tk/src/tkwidget.jl:262
 in init_canvas at /Users/jameson/.julia/Tk/src/tkwidget.jl:295
 in anonymous at /Users/jameson/.julia/Tk/src/tkwidget.jl:274
 in jl_tcl_callback at /Users/jameson/.julia/Tk/src/tkwidget.jl:131
 in tcl_doevent at /Users/jameson/.julia/Tk/src/tkwidget.jl:25
 in wait_initialized at /Users/jameson/.julia/Tk/src/tkwidget.jl:339
 in getgc at /Users/jameson/.julia/Tk/src/tkwidget.jl:348
 in anonymous at /Users/jameson/.julia/Winston/src/tk.jl:46
 in draw at /Users/jameson/.julia/Tk/src/tkwidget.jl:267
 in display at /Users/jameson/.julia/Winston/src/tk.jl:51
 in tk at /Users/jameson/.julia/Winston/src/tk.jl:36
 in _plot at /Users/jameson/.julia/Winston/src/plot.jl:99
 in plot at /Users/jameson/.julia/Winston/src/plot.jl:20

reveal: 
 in reveal at /Users/jameson/.julia/Tk/src/tkwidget.jl:322
 in anonymous at /Users/jameson/.julia/Tk/src/tkwidget.jl:276
 in jl_tcl_callback at /Users/jameson/.julia/Tk/src/tkwidget.jl:131
 in tcl_doevent at /Users/jameson/.julia/Tk/src/tkwidget.jl:25
 in reveal at /Users/jameson/.julia/Tk/src/tkwidget.jl:329
 in draw at /Users/jameson/.julia/Tk/src/tkwidget.jl:268
 in configure at /Users/jameson/.julia/Tk/src/tkwidget.jl:262
 in init_canvas at /Users/jameson/.julia/Tk/src/tkwidget.jl:295
 in anonymous at /Users/jameson/.julia/Tk/src/tkwidget.jl:274
 in jl_tcl_callback at /Users/jameson/.julia/Tk/src/tkwidget.jl:131
 in tcl_doevent at /Users/jameson/.julia/Tk/src/tkwidget.jl:25
 in wait_initialized at /Users/jameson/.julia/Tk/src/tkwidget.jl:339
 in getgc at /Users/jameson/.julia/Tk/src/tkwidget.jl:348
 in anonymous at /Users/jameson/.julia/Winston/src/tk.jl:46
 in draw at /Users/jameson/.julia/Tk/src/tkwidget.jl:267
 in display at /Users/jameson/.julia/Winston/src/tk.jl:51
 in tk at /Users/jameson/.julia/Winston/src/tk.jl:36
 in _plot at /Users/jameson/.julia/Winston/src/plot.jl:99
 in plot at /Users/jameson/.julia/Winston/src/plot.jl:20

reveal: 
 in reveal at /Users/jameson/.julia/Tk/src/tkwidget.jl:322
 in draw at /Users/jameson/.julia/Tk/src/tkwidget.jl:268
 in display at /Users/jameson/.julia/Winston/src/tk.jl:51
 in tk at /Users/jameson/.julia/Winston/src/tk.jl:36
 in _plot at /Users/jameson/.julia/Winston/src/plot.jl:99
 in plot at /Users/jameson/.julia/Winston/src/plot.jl:20
<plot>

julia> plot(1:10)
reveal: 
 in reveal at /Users/jameson/.julia/Tk/src/tkwidget.jl:322
 in draw at /Users/jameson/.julia/Tk/src/tkwidget.jl:268
 in display at /Users/jameson/.julia/Winston/src/tk.jl:51
 in tk at /Users/jameson/.julia/Winston/src/tk.jl:36
 in _plot at /Users/jameson/.julia/Winston/src/plot.jl:99
 in plot at /Users/jameson/.julia/Winston/src/plot.jl:20
<plot>

julia>  --- cause 1 resize event --
reveal: 
 in reveal at /Users/jameson/.julia/Tk/src/tkwidget.jl:322
 in draw at /Users/jameson/.julia/Tk/src/tkwidget.jl:268
 in configure at /Users/jameson/.julia/Tk/src/tkwidget.jl:262
 in anonymous at /Users/jameson/.julia/Tk/src/tkwidget.jl:278
 in jl_tcl_callback at /Users/jameson/.julia/Tk/src/tkwidget.jl:131
 in tcl_doevent at /Users/jameson/.julia/Tk/src/tkwidget.jl:25
 in _uv_hook_asynccb at stream.jl:398
 in process_events at stream.jl:455
 in event_loop at multi.jl:1449
 in anonymous at client.jl:305

reveal: 
 in reveal at /Users/jameson/.julia/Tk/src/tkwidget.jl:322
 in anonymous at /Users/jameson/.julia/Tk/src/tkwidget.jl:276
 in jl_tcl_callback at /Users/jameson/.julia/Tk/src/tkwidget.jl:131
 in tcl_doevent at /Users/jameson/.julia/Tk/src/tkwidget.jl:25
 in reveal at /Users/jameson/.julia/Tk/src/tkwidget.jl:329
 in draw at /Users/jameson/.julia/Tk/src/tkwidget.jl:268
 in configure at /Users/jameson/.julia/Tk/src/tkwidget.jl:262
 in anonymous at /Users/jameson/.julia/Tk/src/tkwidget.jl:278
 in jl_tcl_callback at /Users/jameson/.julia/Tk/src/tkwidget.jl:131
 in tcl_doevent at /Users/jameson/.julia/Tk/src/tkwidget.jl:25
 in _uv_hook_asynccb at stream.jl:398
 in process_events at stream.jl:455
 in event_loop at multi.jl:1449
 in anonymous at client.jl:305

reveal: 
 in reveal at /Users/jameson/.julia/Tk/src/tkwidget.jl:322
 in anonymous at /Users/jameson/.julia/Tk/src/tkwidget.jl:276
 in jl_tcl_callback at /Users/jameson/.julia/Tk/src/tkwidget.jl:131
 in tcl_doevent at /Users/jameson/.julia/Tk/src/tkwidget.jl:25
 in reveal at /Users/jameson/.julia/Tk/src/tkwidget.jl:329
 in anonymous at /Users/jameson/.julia/Tk/src/tkwidget.jl:276
 in jl_tcl_callback at /Users/jameson/.julia/Tk/src/tkwidget.jl:131
 in tcl_doevent at /Users/jameson/.julia/Tk/src/tkwidget.jl:25
 in reveal at /Users/jameson/.julia/Tk/src/tkwidget.jl:329
 in draw at /Users/jameson/.julia/Tk/src/tkwidget.jl:268
 in configure at /Users/jameson/.julia/Tk/src/tkwidget.jl:262
 in anonymous at /Users/jameson/.julia/Tk/src/tkwidget.jl:278
 in jl_tcl_callback at /Users/jameson/.julia/Tk/src/tkwidget.jl:131
 in tcl_doevent at /Users/jameson/.julia/Tk/src/tkwidget.jl:25
 in _uv_hook_asynccb at stream.jl:398
 in process_events at stream.jl:455
 in event_loop at multi.jl:1449
 in anonymous at client.jl:305

[JeffBezanson]

Looks like reveal calling tcl_doevent is handling the next event, which seems to be maybe an expose event like I thought. There seem to be 2 expose events though; not sure why.
Maybe when draw is called by configure it should not call reveal.