Add configuration option for disabling mouse warping

This patch adds a new configuration option "mouse_warping [output|none]".

When mouse warping is disabled, mouse cursor does not jump to middle of current
screen when changing workspaces between multiple outputs. This introduces a
"special" cursor state, where focus is in one window and cursor on another.
Useful for eg. scrolling a web page with mouse wheel while typing into another
window on keyboard.

include/config.h

@@ -109,6 +109,16 @@ struct Config {
      * It is not planned to add any different focus models. */
     bool disable_focus_follows_mouse;
 
+    /** By default, when switching focus to a window on a different output
+     * (e.g. focusing a window on workspace 3 on output VGA-1, coming from
+     * workspace 2 on LVDS-1), the mouse cursor is warped to the center of
+     * that window.
+     *
+     * With the mouse_warping option, you can control when the mouse cursor
+     * should be warped. "none" disables warping entirely, whereas "output"
+     * is the default behavior described above. */
+    warping_t mouse_warping;
+
     /** Remove borders if they are adjacent to the screen edge.
      * This is useful if you are reaching scrollbar on the edge of the
      * screen or do not want to waste a single pixel of displayspace.

include/config_directives.h

@@ -46,6 +46,7 @@ CFGFUN(default_orientation, const char *orientation);
 CFGFUN(workspace_layout, const char *layout);
 CFGFUN(workspace_back_and_forth, const char *value);
 CFGFUN(focus_follows_mouse, const char *value);
+CFGFUN(mouse_warping, const char *value);
 CFGFUN(force_focus_wrapping, const char *value);
 CFGFUN(force_xinerama, const char *value);
 CFGFUN(fake_outputs, const char *outputs);

include/data.h

@@ -99,6 +99,14 @@ typedef enum {
     B_MOUSE = 1
 } input_type_t;
 
+/**
+ * Mouse pointer warping modes.
+ */
+typedef enum {
+    POINTER_WARPING_OUTPUT = 0,
+    POINTER_WARPING_NONE = 1
+} warping_t;
+
 /**
  * Stores a rectangle, for example the size of a window, the child window etc.
  * It needs to be packed so that the compiler will not add any padding bytes.