I seem to unable to create a control in a subroutine and then immediately destroy it if a condition is true.

I assume this is a moot point by now, since the show/hide approach is best, but here it is, for posterity :)

Your code does not attempt to do that

Ignoring that for a minute, this is common for all GUI frameworks, when MainLoop is running, calling Destroy from a callback doesn't actually destroy a window immediately, it schedules it for destruction. See

• wxWindow::Destroy
• Window Deletion overview
• How Events are Processed
• wxApp::Pending
• wxApp::Dispatch

Now back to the code, this will show you the error

sub button_click {
    $hit++;     
    warn "hit $hit ";
    my $warning = Wx::StaticText->new($status, -1, "Input Error $hit "
+,,[3,8]);
    $warning->SetForegroundColour(wxRED);

    if ($hit % 2) {
        $status->SetStatusText("", 0);
        $warning->Show;
    } 
    else {
        $warning->Destroy;
        $status->SetStatusText("OK", 0);
    }    
    warn "[\n", map({ "\t$_,\n" } $status->GetChildren ), "\] ";
}
[download]

The output is

$ perl wx.904074.event.pl
hit 2  at wx.904074.event.pl line 34.
[
]  at wx.904074.event.pl line 46.
hit 3  at wx.904074.event.pl line 34.
[
        Wx::StaticText=HASH(0xed4c34),
]  at wx.904074.event.pl line 46.
hit 4  at wx.904074.event.pl line 34.
[
        Wx::StaticText=HASH(0xed4c34),
]  at wx.904074.event.pl line 46.
hit 5  at wx.904074.event.pl line 34.
[
        Wx::StaticText=HASH(0xed4c34),
        Wx::StaticText=HASH(0xed4be4),
]  at wx.904074.event.pl line 46.
hit 6  at wx.904074.event.pl line 34.
[
        Wx::StaticText=HASH(0xed4c34),
        Wx::StaticText=HASH(0xed4be4),
]  at wx.904074.event.pl line 46.
hit 7  at wx.904074.event.pl line 34.
[
        Wx::StaticText=HASH(0xed4c34),
        Wx::StaticText=HASH(0xed4be4),
        Wx::StaticText=HASH(0xed4c44),
]  at wx.904074.event.pl line 46.
hit 8  at wx.904074.event.pl line 34.
[download]

With each iteration you're creating a new statictext, but you only Destroy it every other iteration, so the list of statictext objects keeps growing.