"ASSERTION: How'd we get a floated inline frame?"

[Tom Copeland <tom infoether com>]

Hi folks -

I'm getting a "ASSERTION: How'd we get a floated inline frame?" message
from a small embedded Mozilla program... everything seems to work OK,
but it makes me kind of nervous.  The program does this, more or less:

=======================
GtkWindow* window = (GtkWindow*)gtk_window_new(GTK_WINDOW_TOPLEVEL);
gtk_widget_set_size_request((GtkWidget*)window, 640, 480);
gtk_window_set_position(window, GTK_WIN_POS_CENTER);
gtk_window_set_decorated(window, FALSE);
moz = gtk_moz_embed_new(); // gtkmozembed used here
vbox = gtk_vbox_new(FALSE, 0);
gtk_container_add(GTK_CONTAINER(window), vbox);
gtk_box_pack_start(GTK_BOX(vbox), moz, TRUE, TRUE, 0);
gtk_widget_show_all((GtkWidget*)window);
=======================

and here's the complete message:

=======================
###!!! ASSERTION: How'd we get a floated inline frame? The frame ctor
should've dealt with this.: 'aReflowState.mStyleDisplay->mFloats ==
NS_STYLE_FLOAT_NONE', file nsLineLayout.cpp, line 1314
=======================

and here's the code snippet from nsLineLayout:

=======================
  NS_PRECONDITION(pfd && pfd->mFrame, "bad args, null pointers for frame
data");
  // Compute right margin to use
  if (0 != pfd->mBounds.width) {
    NS_ASSERTION(aReflowState.mStyleDisplay->mFloats ==
NS_STYLE_FLOAT_NONE,
                 "How'd we get a floated inline frame? "
                 "The frame ctor should've dealt with this.");
=======================

Any ideas?  Is this something that'll haunt me down the road?

Thanks much,

Tom Copeland