Document restrictions when setting window margins, fringes or scroll bars

* src/window.c (Fset_window_margins, Fset_window_fringes)
(Fset_window_scroll_bars): In doc-strings tell that a window
must be large enough to accommodate fringes, sroll bars and
margins of the desired size.
* doc/lispref/display.texi (Fringe Size/Pos, Scroll Bars)
(Display Margins): Tell that windows must be large enough to
accommodate fringes, sroll bars and margins of the desired
size.

1 files changed, 9 insertions, 0 deletions

diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index 7892c15b462..e3ee62ffb68 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -3916,6 +3916,9 @@ fringe, and likewise @var{right} for the right fringe.  A value of
 @var{outside-margins} is non-@code{nil}, that specifies that fringes
 should appear outside of the display margins.
 
+If @var{window} is not large enough to accommodate fringes of the
+desired width, this leaves the fringes of @var{window} unchanged.
+
 The values specified here may be later overridden by invoking
 @code{set-window-buffer} (@pxref{Buffers and Windows}) on @var{window}
 with its @var{keep-margins} argument @code{nil} or omitted.
@@ -4337,6 +4340,9 @@ vertical scroll bar.
 The possible values are @code{bottom}, @code{t}, which means to use the
 frame's default, and @code{nil} for no horizontal scroll bar.
 
+If @var{window} is not large enough to accommodate a scroll bar of the
+desired dimension, this leaves the corresponding scroll bar unchanged.
+
 The values specified here may be later overridden by invoking
 @code{set-window-buffer} (@pxref{Buffers and Windows}) on @var{window}
 with its @var{keep-margins} argument @code{nil} or omitted.
@@ -4926,6 +4932,9 @@ This function specifies the margin widths for window @var{window}, in
 character cell units.  The argument @var{left} controls the left
 margin, and @var{right} controls the right margin (default @code{0}).
 
+If @var{window} is not large enough to accommodate margins of the
+desired width, this leaves the margins of @var{window} unchanged.
+
 The values specified here may be later overridden by invoking
 @code{set-window-buffer} (@pxref{Buffers and Windows}) on @var{window}
 with its @var{keep-margins} argument @code{nil} or omitted.