Mention `frame-resize-pixelwise' to make frames truly fullscreen or maximized.

* frame.el (toggle-frame-maximized, toggle-frame-fullscreen):
In doc-string mention need of setting `frame-resize-pixelwise'.

* frames.texi (Frame Commands):
* cmdargs.texi (Window Size X): Mention the use of
`frame-resize-pixelwise' to make frames truly fullscreen or
maximized.

* frames.texi (Size Parameters, Size and Position): Mention that
with some window managers you have to set
`frame-resize-pixelwise' in order make a frame truly fullscreen
or maximized.

doc/emacs/ChangeLog

@@ -1,3 +1,10 @@
+2014-10-03  Martin Rudalics  <rudalics@gmx.at>
+
+	* frames.texi (Frame Commands):
+	* cmdargs.texi (Window Size X): Mention the use of
+	`frame-resize-pixelwise' to make frames truly fullscreen or
+	maximized.
+
 2014-10-01  Glenn Morris  <rgm@gnu.org>
 
 	* package.texi (Package Installation): Mention etc/package-keyring.gpg.

doc/emacs/cmdargs.texi

@@ -987,10 +987,10 @@ size with no tool bar, use an X resource to specify ``no tool bar''
 (@pxref{Table of Resources}); then Emacs will already know there's no
 tool bar when it processes the specified geometry.
 
-  When using one of @samp{--fullscreen}, @samp{--maximized}, @samp{--fullwidth}
-or @samp{--fullheight} there may be some space around the frame
-anyway.  That is because Emacs rounds the sizes so they are an
-even number of character heights and widths.
+  When using one of @samp{--fullscreen}, @samp{--maximized},
+@samp{--fullwidth} or @samp{--fullheight}, some window managers require
+to set the variable @code{frame-resize-pixelwise} to a non-@code{nil}
+value to make a frame appear truly ``maximized'' or ``fullscreen''.
 
  Some window managers have options that can make them ignore both
 program-specified and user-specified positions.  If these are set,

doc/emacs/frames.texi

@@ -469,6 +469,10 @@ hides window manager decorations, giving slightly more screen space to
 Emacs itself.)
 @end table
 
+  Note that with some window managers you may have to customize the
+variable @code{frame-resize-pixelwise} to a non-@code{nil} value in
+order to make a frame truly ``maximized'' or ``fullscreen''.
+
   The @kbd{C-x 5 0} (@code{delete-frame}) command deletes the selected
 frame.  However, it will refuse to delete the last frame in an Emacs
 session, to prevent you from losing the ability to interact with the

doc/lispref/ChangeLog

@@ -1,3 +1,10 @@
+2014-10-03  Martin Rudalics  <rudalics@gmx.at>
+
+	* frames.texi (Size Parameters, Size and Position): Mention that
+	with some window managers you have to set
+	`frame-resize-pixelwise' in order make a frame truly fullscreen
+	or maximized.
+
 2014-09-04  Stefan Monnier  <monnier@iro.umontreal.ca>
 
 	* functions.texi (Core Advising Primitives): Add a note about the

doc/lispref/frames.texi

@@ -686,6 +686,11 @@ difference between @code{maximized} and @code{fullboth} is that the
 former can still be resized by dragging window manager decorations
 with the mouse, while the latter really covers the whole screen and
 does not allow resizing by mouse dragging.
+
+With some window managers you may have to customize the variable
+@code{frame-resize-pixelwise} to a non-@code{nil} value in order to make
+a frame appear ``maximized'' or ``fullscreen''.
+
 @end table
 
 @node Layout Parameters
@@ -1163,7 +1168,10 @@ on the toolkit used: Dragging the frame border with the mouse is usually
 always done character-wise.  Calling @code{set-frame-size} (see below)
 with arguments that do not specify the frame size as an integer multiple
 of its character size may be, however, either ignored or cause a
-rounding (GTK+, Windows) or get accepted (Lucid, Motif).
+rounding (GTK+) or get accepted (Lucid, Motif, Windows).
+
+With some window managers you may have to set this to non-@code{nil} in
+order to make a frame appear truly ``maximized'' or ``fullscreen''.
 @end defopt
 
 @defun set-frame-size frame width height pixelwise

lisp/ChangeLog

@@ -1,3 +1,8 @@
+2014-10-03  Martin Rudalics  <rudalics@gmx.at>
+
+	* frame.el (toggle-frame-maximized, toggle-frame-fullscreen):
+	In doc-string mention need of setting `frame-resize-pixelwise'.
+
 2014-10-03  Stefan Monnier  <monnier@iro.umontreal.ca>
 
 	* vc/vc-svn.el (vc-svn-after-dir-status): Fix the non-remote regexp,

lisp/frame.el

@@ -1844,6 +1844,11 @@ If the frame is in fullscreen mode, don't change its mode,
 just toggle the temporary frame parameter `maximized',
 so the frame will go to the right maximization state
 after disabling fullscreen mode.
+
+Note that with some window managers you may have to set
+`frame-resize-pixelwise' to non-nil in order to make a frame
+appear truly maximized.
+
 See also `toggle-frame-fullscreen'."
   (interactive)
   (if (memq (frame-parameter nil 'fullscreen) '(fullscreen fullboth))
@@ -1865,6 +1870,11 @@ already fullscreen.  Ignore window manager screen decorations.
 When turning on fullscreen mode, remember the previous value of the
 maximization state in the temporary frame parameter `maximized'.
 Restore the maximization state when turning off fullscreen mode.
+
+Note that with some window managers you may have to set
+`frame-resize-pixelwise' to non-nil in order to make a frame
+appear truly fullscreen.
+
 See also `toggle-frame-maximized'."
   (interactive)
   (modify-frame-parameters