bug#62135: xterm.c: (x_set_offset)

[Madhu]

While investingating some persistent placements at 0x0 by some wm, I was
looking at x-set-offset, (which gets called via x_make_frame_visible).

In the code below there is a comment that documents the role of the
change_gravity argument.  When called from x_make_frame_visible the
parameter is set to 0, so as not to do anything. However lines
22713-22720 perform an unconditional move window, which happens in
this code path even before the XWindow the mapped.

1) Shouldn't these lines be protected by a "if (change_gravity != 0) {
... }" conditional?

My surmise is that most wms ignore the call to XMoveWindow because it is
unmapped but at least wayfire (on Xwayland) persistently seems to
position it at 0, 0 as the code calls it.

Also the 0x0 placement only happens on non-gtk builds, because I think
there is another bug in lines 22689-22702. x_gtk_use_window_move is
always true and gtk builds exit x_set_offset before reaching that
line.

I hope martin can pick this up from here and take a look?
---Regards, Madhu

```
 22663  /* CHANGE_GRAVITY is 1 when calling from Fset_frame_position,
 22664     to really change the position, and 0 when calling from
 22665     x_make_frame_visible (in that case, XOFF and YOFF are the current
 22666     position values).  It is -1 when calling from 
gui_set_frame_parameters,
 22667     which means, do adjust for borders but don't change the gravity.  */

 22668  static void
 22669  x_set_offset (struct frame *f, int xoff, int yoff, int change_gravity)
 22670  {
 22671    int modified_top, modified_left;
 22672  #ifdef USE_GTK
 22673    int scale = xg_get_scale (f);
 22674  #endif

 22675    if (change_gravity > 0)
 22676      {
[...]

 22689  #ifdef USE_GTK
 22690    if (x_gtk_use_window_move)
 22691      {
 22692        /* When a position change was requested and the outer GTK widget
 22693           has been realized already, leave it to gtk_window_move to
 22694           DTRT and return.  Used for Bug#25851 and Bug#25943.  Convert
 22695           from X pixels to GTK scaled pixels.  */
 22696        if (change_gravity != 0 && FRAME_GTK_OUTER_WIDGET (f))
 22697          gtk_window_move (GTK_WINDOW (FRAME_GTK_OUTER_WIDGET (f)),
 22698                           f->left_pos / scale, f->top_pos / scale);
 22699        unblock_input ();
 22700        return;
 22701      }
 22702  #endif /* USE_GTK */

 22703    modified_left = f->left_pos;
 22704    modified_top = f->top_pos;

 22705    if (change_gravity != 0 && FRAME_DISPLAY_INFO (f)->wm_type == 
X_WMTYPE_A)
 22706      {
 22707        /* Some WMs (twm, wmaker at least) has an offset that is smaller
 22708           than the WM decorations.  So we use the calculated offset 
instead
 22709           of the WM decoration sizes here (x/y_pixels_outer_diff).  */
 22710        modified_left += FRAME_X_OUTPUT (f)->move_offset_left;
 22711        modified_top += FRAME_X_OUTPUT (f)->move_offset_top;
 22712      }

 22713  #ifdef USE_GTK
 22714    /* Make sure we adjust for possible scaling.  */
 22715    gtk_window_move (GTK_WINDOW (FRAME_GTK_OUTER_WIDGET (f)),
 22716                     modified_left / scale, modified_top / scale);
 22717  #else
 22718    XMoveWindow (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f),
 22719                 modified_left, modified_top);
 22720  #endif

```

In GNU Emacs 30.0.50 (build 2, x86_64-pc-linux-gnu, X toolkit, cairo
 version 1.16.0, Xaw3d scroll bars) of 2023-02-14
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