rules: handle missing libX11 more gracefully and document dependency

docs/index.md

@@ -136,10 +136,6 @@ for the step-by-step procedure for manual installation.
 - Sometimes the system tray icon does not show up.  The cause of this is unknown.
   Either wait a while and try again or try with the `--window=hide` option.
 
-- Running the command-line application while the GUI
-  application is also running *may* occasionally cause either of them to become
-  confused about the state of the devices.
-
 - Some Linux drivers view or modify the setting Scroll Wheel Resolution to
   implement smooth scrolling.  If Solaar changes this setting after the driver is
   set up scrolling can be either very fast or very slow.  To fix this problem
@@ -156,6 +152,8 @@ for the step-by-step procedure for manual installation.
   but this needs write permission on /dev/uinput.
   For more information see [the rules page](https://pwr-solaar.github.io/Solaar/rules).
 
+- Sometimes bluetooth connections are not torn down correctly.
+  This can result in two entries in Solaar for the same device, with only one being active.
 
 ## Contributing to Solaar
 

docs/installation.md

@@ -35,6 +35,13 @@ depending on your distribution).
 If you are running a version of Python different from the system version,
 you may need to use pip to install projects that provide the above Python packages.
 
+Solaar runs best under X11 with the Xtest extension enabled so that Solaar rules can fake keyboard input using Xtest.
+Solaar also uses the X11 library to access the XKB extension,
+which requires installation of the X11 development package.
+(In Fedora this is `libX11-devel`.  In other distributions it may be `libX11-dev`.)
+Solaar will run under Wayland but some parts of Solaar rules will not work.
+For more information see [the rules page](https://pwr-solaar.github.io/Solaar/rules).
+
 If desktop notifications bindings are also installed
 (`gir1.2-notify-0.7` for Debian/Ubuntu),
 you will also see desktop notifications when devices come online/go offline.

lib/logitech_receiver/diversion.py

@@ -80,6 +80,16 @@ try:
     NET_WM_PID = xdisplay.intern_atom('_NET_WM_PID')
     WM_CLASS = xdisplay.intern_atom('WM_CLASS')
 
+except Exception:
+    _log.warn(
+        'X11 not available - rules cannot access current process, modifier keys, or keyboard group. %s',
+        exc_info=_sys.exc_info()
+    )
+    modifier_keycodes = []
+    x11 = False
+
+if x11:
+    try:
         # set up to get keyboard state using ctypes interface to libx11
         import ctypes
 
@@ -99,17 +109,14 @@ try:
         X11Lib.XOpenDisplay.restype = ctypes.POINTER(XkbDisplay)
         X11Lib.XkbGetState.argtypes = [ctypes.POINTER(XkbDisplay), ctypes.c_uint, ctypes.POINTER(XkbStateRec)]
         Xkbdisplay = X11Lib.XOpenDisplay(None)
-except Exception:
+
-    _log.warn(
+    except Exception:
-        'X11 not available - rules cannot access current process, modifier keys, or keyboard group. %s',
+        _log.warn('X11 library not available - rules cannot access keyboard group. %s', exc_info=_sys.exc_info())
-        exc_info=_sys.exc_info()
+        Xkbdisplay = None
-    )
-    modifier_keycodes = []
-    x11 = False
 
 
 def kbdgroup():
-    if x11:
+    if Xkbdisplay:
         state = XkbStateRec()
         X11Lib.XkbGetState(Xkbdisplay, XkbUseCoreKbd, ctypes.pointer(state))
         return state.group