Confused about wxWindow::Update() vs Refresh()

[Paul Melis]

Hello,

I have a situation in which an event handler (File -> Open) starts the 
processing of some data by an external library. The library provides 
progress callbacks which I'm using to drive a progress bar.
But how can I force redrawing of the progress bar immediately without 
using Yield()? Is this possible at all?

 From the description of wxWindow::Update() and wxWindow::Refresh() in 
the 2.8 docs (see below) I get a confused picture of what to do.

For Refresh() it says
"Causes this window, and all of its children recursively [...], to be 
repainted. Note that repainting doesn't happen immediately but only 
during the next event loop iteration, if you need to update the window 
immediately you should use Update instead."

So this would seem to suggest that calling Update() would force an 
immediate update (repaint), but for Update() it reads:
"Calling this method immediately repaints the invalidated area of the 
window and all of its children recursively while this would usually only 
happen when the flow of control returns to the event loop. Notice that 
this function doesn't refresh the window and does nothing if the window 
hadn't been already repainted. Use Refresh first if you want to 
immediately redraw the window unconditionally."

The second part of the sentence "Notice that this function doesn't 
refresh the window and does nothing if the window hadn't been already 
repainted." is extremely confusing. Update() does nothing if there has 
NOT already been a repaint?? Should I actually read this as "This 
function doesn't _refresh_ the window (call Refresh() for that first). 
This function does nothing if the window already has been repainted"?

It seems that calling Refresh() on the progress first, to force it to 
repaint, followed by a call to Update() would do the trick but it 
doesn't (i.e. no redrawing takes place).

This is with wxGTK (2.6) b.t.w.

Paul