Major rework of prompts. The basic prompt mechanics (draw, editing, etc)

are now wrapped up in prompt*.c and do not depend on a client. These
functions are used to provide the original client prompt but also to
allow panes to have their own prompts, which works much much better for
floating panes. The mode prompts for both the tree modes and copy mode
are switched over to be per pane.

There are some visible changes (some of these may be changed if they
don't seem to be working well):

- Prompts in modes now appear in the bottom line, covering whatever
  content was there.

- command-prompt has a -P flag to open a pane prompt.

- Because they cover the content, the default style for prompts in modes
  now does not fill the entire line; the main command prompt stays the
  same.

- The old completion menu has gone, and completions are now shown after
  the text. Builtin aliases are no longer completed.

- Clicking the mouse on the prompt now moves the cursor or selects a
  completion.

window.c

@@ -80,6 +80,14 @@ RB_GENERATE(windows, window, entry, window_cmp);
 RB_GENERATE(winlinks, winlink, entry, winlink_cmp);
 RB_GENERATE(window_pane_tree, window_pane, tree_entry, window_pane_cmp);
 
+struct window_pane_prompt {
+	u_int			 wp_id;
+	struct client		*c;
+	status_prompt_input_cb	 inputcb;
+	prompt_free_cb		 freecb;
+	void			*data;
+};
+
 int
 window_cmp(struct window *w1, struct window *w2)
 {
@@ -1148,6 +1156,8 @@ window_pane_destroy(struct window_pane *wp)
 	window_pane_wait_finish(wp);
 	spawn_editor_finish(wp);
 
+	window_pane_clear_prompt(wp);
+
 	window_pane_free_modes(wp);
 	free(wp->searchstr);
 
@@ -1360,6 +1370,7 @@ window_pane_reset_mode(struct window_pane *wp)
 		server_kill_pane(wp);
 }
 
+/* Reset all modes. */
 void
 window_pane_reset_mode_all(struct window_pane *wp)
 {
@@ -1367,6 +1378,165 @@ window_pane_reset_mode_all(struct window_pane *wp)
 		window_pane_reset_mode(wp);
 }
 
+/* Prompt input callback. */
+static enum prompt_result
+window_pane_prompt_input_callback(void *data, const char *s,
+    enum prompt_key_result key)
+{
+	struct window_pane_prompt	*wpp = data;
+
+	if (wpp->inputcb != NULL)
+		return (wpp->inputcb(wpp->c, wpp->data, s, key));
+	return (PROMPT_CLOSE);
+}
+
+/* Prompt free callback. */
+static void
+window_pane_prompt_free_callback(void *data)
+{
+	struct window_pane_prompt	*wpp = data;
+	struct window_pane		*wp;
+
+	wp = window_pane_find_by_id(wpp->wp_id);
+	if (wp != NULL && wp->prompt_data == wpp)
+		wp->prompt_data = NULL;
+	if (wpp->freecb != NULL)
+		wpp->freecb(wpp->data);
+	free(wpp);
+}
+
+/* Open a prompt owned by a pane, drawn over the pane instead of the status. */
+void
+window_pane_set_prompt(struct window_pane *wp, struct client *c,
+    struct cmd_find_state *fs, const char *msg, const char *input,
+    status_prompt_input_cb inputcb, prompt_free_cb freecb, void *data,
+    int flags, enum prompt_type type)
+{
+	struct session			*s = NULL;
+	struct prompt_create_data	 pd;
+	struct window_pane_prompt	*wpp;
+
+	if (c != NULL)
+		s = c->session;
+
+	window_pane_clear_prompt(wp);
+
+	wpp = xcalloc(1, sizeof *wpp);
+	wpp->wp_id = wp->id;
+	wpp->c = c;
+	wpp->inputcb = inputcb;
+	wpp->freecb = freecb;
+	wpp->data = data;
+
+	memset(&pd, 0, sizeof pd);
+	prompt_set_options(&pd, s);
+	pd.fs = fs;
+	pd.prompt = msg;
+	pd.input = input;
+	pd.type = type;
+	pd.flags = flags;
+	pd.inputcb = window_pane_prompt_input_callback;
+	pd.freecb = window_pane_prompt_free_callback;
+	pd.data = wpp;
+
+	wp->prompt = prompt_create(&pd);
+	wp->prompt_data = wpp;
+	wp->flags |= PANE_REDRAW;
+
+	prompt_incremental_start(wp->prompt);
+}
+
+/* Close a pane prompt. */
+void
+window_pane_clear_prompt(struct window_pane *wp)
+{
+	struct prompt	*prompt = wp->prompt;
+
+	if (prompt == NULL)
+		return;
+	wp->prompt = NULL;
+	prompt_free(prompt);
+	wp->flags |= PANE_REDRAW;
+}
+
+/* Does this pane have an open prompt? */
+int
+window_pane_has_prompt(struct window_pane *wp)
+{
+	return (wp->prompt != NULL);
+}
+
+/* Replace the message and input of an open pane prompt. */
+void
+window_pane_update_prompt(struct window_pane *wp, const char *msg,
+    const char *input)
+{
+	if (wp->prompt != NULL) {
+		prompt_update(wp->prompt, msg, input);
+		wp->flags |= PANE_REDRAW;
+	}
+}
+
+/*
+ * Pass a key to a pane prompt. The client is set transiently for the duration
+ * of the key in case the prompt or pane is destroyed by the callback.
+ */
+enum prompt_key_result
+window_pane_prompt_key(struct window_pane *wp, struct client *c, key_code key,
+    struct mouse_event *m)
+{
+	struct prompt			*prompt = wp->prompt;
+	struct window_pane_prompt	*wpp = wp->prompt_data;
+	enum prompt_key_result		 result;
+	u_int				 wp_id = wp->id, x, y, py;
+	int				 redraw = 0;
+
+	if (prompt == NULL)
+		return (PROMPT_KEY_NOT_HANDLED);
+
+	if (wpp != NULL)
+		wpp->c = c;
+	if (KEYC_IS_MOUSE(key)) {
+		if (m == NULL ||
+		    MOUSE_BUTTONS(m->b) != MOUSE_BUTTON_1 ||
+		    MOUSE_DRAG(m->b) ||
+		    MOUSE_RELEASE(m->b) ||
+		    cmd_mouse_at(wp, m, &x, &y, 0) != 0)
+			result = PROMPT_KEY_NOT_HANDLED;
+		else {
+			if (c != NULL && status_at_line(c) == 0)
+				py = 0;
+			else
+				py = wp->sy - 1;
+			if (y == py) {
+				result = prompt_mouse(prompt, x, 0, wp->sx,
+				    &redraw);
+			} else
+				result = PROMPT_KEY_NOT_HANDLED;
+		}
+	} else
+		result = prompt_key(prompt, key, &redraw);
+
+	wp = window_pane_find_by_id(wp_id);
+	if (wp == NULL)
+		return (result);
+	if (wpp != NULL && wp->prompt_data == wpp)
+		wpp->c = NULL;
+
+	/*
+	 * Only an explicit close or the prompt marking itself closed ends it;
+	 * cursor movement and editing keep it open.
+	 */
+	if (wp->prompt == prompt &&
+	    (result == PROMPT_KEY_CLOSE || prompt_closed(prompt)))
+		window_pane_clear_prompt(wp);
+
+	if (redraw || wp->prompt != prompt)
+		wp->flags |= PANE_REDRAW;
+
+	return (result);
+}
+
 static void
 window_pane_copy_paste(struct window_pane *wp, char *buf, size_t len)
 {