diff --git a/options-table.c b/options-table.c
index 83e44067..d9918193 100644
--- a/options-table.c
+++ b/options-table.c
@@ -664,6 +664,13 @@ const struct options_table_entry options_table[] = {
 	  .text = "Time for which status line messages should appear."
 	},
 
+	{ .name = "focus-follows-mouse",
+	  .type = OPTIONS_TABLE_FLAG,
+	  .scope = OPTIONS_TABLE_SESSION,
+	  .default_num = 0,
+	  .text = "Whether moving the mouse into a pane selects it."
+	},
+
 	{ .name = "history-limit",
 	  .type = OPTIONS_TABLE_NUMBER,
 	  .scope = OPTIONS_TABLE_SESSION,
diff --git a/server-client.c b/server-client.c
index 7f1942c7..1c41870f 100644
--- a/server-client.c
+++ b/server-client.c
@@ -1060,8 +1060,16 @@ have_event:
 	case NOTYPE:
 		break;
 	case MOVE:
-		if (where == PANE)
+		if (where == PANE) {
 			key = KEYC_MOUSEMOVE_PANE;
+			if (wp != NULL &&
+			    wp != w->active &&
+			    options_get_number(s->options, "focus-follows-mouse")) {
+				window_set_active_pane(w, wp, 1);
+				server_redraw_window_borders(w);
+				server_status_window(w);
+			}
+		}
 		if (where == STATUS)
 			key = KEYC_MOUSEMOVE_STATUS;
 		if (where == STATUS_LEFT)
@@ -2969,7 +2977,8 @@ server_client_reset_state(struct client *c)
 
 	/*
 	 * Set mouse mode if requested. To support dragging, always use button
-	 * mode.
+	 * mode. For focus-follows-mouse, we need all-motion mode to receive
+	 * movement events.
 	 */
 	if (options_get_number(oo, "mouse")) {
 		if (c->overlay_draw == NULL) {
@@ -2979,7 +2988,9 @@ server_client_reset_state(struct client *c)
 					mode |= MODE_MOUSE_ALL;
 			}
 		}
-		if (~mode & MODE_MOUSE_ALL)
+		if (options_get_number(oo, "focus-follows-mouse"))
+			mode |= MODE_MOUSE_ALL;
+		else if (~mode & MODE_MOUSE_ALL)
 			mode |= MODE_MOUSE_BUTTON;
 	}
 
diff --git a/tmux.1 b/tmux.1
index 3085fb85..b8acaa38 100644
--- a/tmux.1
+++ b/tmux.1
@@ -4244,6 +4244,12 @@ passed through to applications running in
 .Nm .
 Attached clients should be detached and attached again after changing this
 option.
+.It Xo Ic focus-follows-mouse
+.Op Ic on | off
+.Xc
+When enabled and
+.Ic mouse
+is on, moving the mouse into a pane selects it.
 .It Xo Ic get-clipboard
 .Op Ic both | request | buffer | off
 .Xc
@@ -6240,6 +6246,7 @@ The following variables are available, where appropriate:
 .It Li "selection_active" Ta "" Ta "1 if selection started and changes with the cursor in copy mode"
 .It Li "selection_end_x" Ta "" Ta "X position of the end of the selection"
 .It Li "selection_end_y" Ta "" Ta "Y position of the end of the selection"
+.It Li "selection_mode" Ta "" Ta "Selection mode"
 .It Li "selection_present" Ta "" Ta "1 if selection started in copy mode"
 .It Li "selection_start_x" Ta "" Ta "X position of the start of the selection"
 .It Li "selection_start_y" Ta "" Ta "Y position of the start of the selection"
diff --git a/window-copy.c b/window-copy.c
index f8700555..87d0dea8 100644
--- a/window-copy.c
+++ b/window-copy.c
@@ -956,6 +956,18 @@ window_copy_formats(struct window_mode_entry *wme, struct format_tree *ft)
 		format_add(ft, "selection_present", "0");
 	}
 
+	switch (data->selflag) {
+	case SEL_CHAR:
+		format_add(ft, "selection_mode", "char");
+		break;
+	case SEL_WORD:
+		format_add(ft, "selection_mode", "word");
+		break;
+	case SEL_LINE:
+		format_add(ft, "selection_mode", "line");
+		break;
+	}
+
 	format_add(ft, "search_present", "%d", data->searchmark != NULL);
 	format_add(ft, "search_timed_out", "%d", data->timeout);
 	if (data->searchcount != -1) {