config: Add "seamless_mouse" to decide if pointer crosses output edges.

include/config.h

@@ -55,6 +55,7 @@ struct sway_config {
 	bool reloading;
 	bool reading;
 	bool auto_back_and_forth;
+	bool seamless_mouse;
 
 	int gaps_inner;
 	int gaps_outer;

sway.5.txt

@@ -112,6 +112,11 @@ Commands
 	Resizes the currently focused container or view by _amount_. _amount_ can be
 	specified as "n px" or "n ppt" or "n px or n ppt".
 
+**seamless_mouse** <on|off>::
+	Change output seamlessly when pointer touches edge of output. Outputs need to
+	be configured with perfectly aligned adjacent positions for this option to
+	have any effect.
+
 **set** <name> <value>::
 	Creates a substitution for _value_ that can be used with $_name_ in other
 	commands.

sway/commands.c

@@ -410,6 +410,15 @@ static enum cmd_status cmd_focus_follows_mouse(int argc, char **argv) {
 	return CMD_SUCCESS;
 }
 
+static enum cmd_status cmd_seamless_mouse(int argc, char **argv) {
+	if (!checkarg(argc, "seamless_mouse", EXPECTED_EQUAL_TO, 1)) {
+		return CMD_FAILURE;
+	}
+
+	config->seamless_mouse = (strcasecmp(argv[0], "on") == 0 || strcasecmp(argv[0], "yes") == 0);
+	return CMD_SUCCESS;
+}
+
 static void hide_view_in_scratchpad(swayc_t *sp_view) {
 	if (sp_view == NULL) {
 		return;
@@ -1139,6 +1148,7 @@ static struct cmd_handler handlers[] = {
 	{ "reload", cmd_reload },
 	{ "resize", cmd_resize },
 	{ "scratchpad", cmd_scratchpad },
+	{ "seamless_mouse", cmd_seamless_mouse },
 	{ "set", cmd_set },
 	{ "split", cmd_split },
 	{ "splith", cmd_splith },

sway/config.c

@@ -102,6 +102,7 @@ static void config_defaults(struct sway_config *config) {
 	config->active = false;
 	config->failed = false;
 	config->auto_back_and_forth = false;
+	config->seamless_mouse = true;
 	config->reading = false;
 
 	config->gaps_inner = 0;

sway/handlers.c

@@ -357,7 +357,7 @@ static bool handle_pointer_motion(wlc_handle handle, uint32_t time, const struct
 	//
 	// Since this doesn't currently support moving windows between outputs we
 	// don't do the switch if the pointer is in a mode.
-	if (!pointer_state.mode) {
+	if (config->seamless_mouse && !pointer_state.mode) {
 		swayc_t *output = swayc_active_output();
 
 		// TODO: This implementation is naïve: We assume all outputs are