Inlined patch adds short timed prompts to status bar about things like
switching between diff algorithms, showing white spaces in patches,
toggling bin/ascii views for blobs, changing committer and author
representations, and switch between date/name sorting for ref view.

Originally I wanted it because I needed to see current diff algorithm,
but decided to expand the patch to show all togglable events, except for
ref view, where, for example, showing IDs speaks for itself by changing
the look of the table and doesn't require a prompt.

diff /home/misha/work/got
commit - 7713cc5e4f5544e81909670d592e89526ed86c9b
path + /home/misha/work/got
blob - 35282ce50aa4dec0745aa6402cd0b50d87b7416b
file + tog/tog.c
--- tog/tog.c
+++ tog/tog.c
@@ -690,6 +690,7 @@ struct tog_view {
 #define TOG_SEARCH_HAVE_NONE	3
 	regex_t regex;
 	regmatch_t regmatch;
+	const char *prompt;
 };
 
 static const struct got_error *open_diff_view(struct tog_view *,
@@ -1476,6 +1477,16 @@ view_input(struct tog_view **new, int *done, struct to
 		view->count = 0;
 	}
 
+	/*
+	 * Clear statusbar prompt, for blame view clear it only when
+	 * annotating is completed, otherwise it's too fast.
+	 */
+	if (view->type == TOG_VIEW_BLAME) {
+		if (view->state.blame.blame_complete)
+			view->prompt = NULL;
+	} else
+		view->prompt = NULL;
+
 	if (view->searching && !view->search_next_done) {
 		errcode = pthread_mutex_unlock(&tog_mutex);
 		if (errcode)
@@ -1668,10 +1679,13 @@ view_input(struct tog_view **new, int *done, struct to
 			err = view->input(new, view, ch);
 		break;
 	case 'A':
-		if (tog_diff_algo == GOT_DIFF_ALGORITHM_MYERS)
+		if (tog_diff_algo == GOT_DIFF_ALGORITHM_MYERS) {
 			tog_diff_algo = GOT_DIFF_ALGORITHM_PATIENCE;
-		else
+			view->prompt = "Patience algorithm";
+		} else {
 			tog_diff_algo = GOT_DIFF_ALGORITHM_MYERS;
+			view->prompt = "Myers algorithm";
+		}
 		TAILQ_FOREACH(v, views, entry) {
 			if (v->reset) {
 				err = v->reset(v);
@@ -2489,10 +2503,11 @@ draw_commits(struct tog_view *view)
 		if (s->limit_view && s->commits->ncommits == 0)
 			limit_str = "no matches found";
 
-		if (asprintf(&ncommits_str, " [%d/%d] %s %s",
+		if (asprintf(&ncommits_str, " [%d/%d] %s %s %s",
 		    entry ? entry->idx + 1 : 0, s->commits->ncommits,
 		    search_str ? search_str : (refs_str ? refs_str : ""),
-		    limit_str ? limit_str : "") == -1) {
+		    (limit_str ? limit_str : ""),
+		    (view->prompt ? view->prompt : "")) == -1) {
 			err = got_error_from_errno("asprintf");
 			goto done;
 		}
@@ -3718,6 +3733,7 @@ input_log_view(struct tog_view **new_view, struct tog_
 		break;
 	case '@':
 		s->use_committer = !s->use_committer;
+		view->prompt = (s->use_committer ? "Committer" : "Author");
 		break;
 	case 'G':
 	case '*':
@@ -5130,7 +5146,8 @@ show_diff_view(struct tog_view *view)
 		return err;
 	label2 = s->label2 ? s->label2 : id_str2;
 
-	if (asprintf(&header, "diff %s %s", label1, label2) == -1) {
+	if (asprintf(&header, "diff %s %s %s", label1, label2,
+	    (view->prompt ? view->prompt : "")) == -1) {
 		err = got_error_from_errno("asprintf");
 		free(id_str1);
 		free(id_str2);
@@ -5261,10 +5278,17 @@ input_diff_view(struct tog_view **new_view, struct tog
 		break;
 	case 'a':
 	case 'w':
-		if (ch == 'a')
+		if (ch == 'a') {
 			s->force_text_diff = !s->force_text_diff;
-		else if (ch == 'w')
+			view->prompt =
+			    (s->force_text_diff ? "Text diff" : "Bin diff");
+		}
+		else if (ch == 'w') {
 			s->ignore_whitespace = !s->ignore_whitespace;
+			view->prompt =
+			    (s->ignore_whitespace ?
+			    "Ignore whitespaces" : "Show whitespaces");
+		}
 		err = reset_diff_view(view);
 		break;
 	case 'g':
@@ -5621,12 +5645,16 @@ draw_blame(struct tog_view *view)
 	rewind(blame->f);
 	werase(view->window);
 
-	if (asprintf(&line, "commit %s", id_str) == -1) {
+	if (asprintf(&line, "commit %s %s", id_str,
+	    (view->prompt ? view->prompt : "")) == -1) {
 		err = got_error_from_errno("asprintf");
 		free(id_str);
 		return err;
 	}
 
+	if (s->blame_complete)
+		view->prompt = NULL;
+
 	err = format_line(&wline, &width, NULL, line, 0, view->ncols, 0, 0);
 	free(line);
 	line = NULL;
@@ -8006,8 +8034,8 @@ show_ref_view(struct tog_view *view)
 
 	re = s->first_displayed_entry;
 
-	if (asprintf(&line, "references [%d/%d]", re->idx + s->selected + 1,
-	    s->nrefs) == -1)
+	if (asprintf(&line, "references [%d/%d] %s", re->idx + s->selected + 1,
+	    s->nrefs, (view->prompt ? view->prompt : "")) == -1)
 		return got_error_from_errno("asprintf");
 
 	err = format_line(&wline, &width, NULL, line, 0, view->ncols, 0, 0);
@@ -8233,6 +8261,8 @@ input_ref_view(struct tog_view **new_view, struct tog_
 		break;
 	case 'o':
 		s->sort_by_date = !s->sort_by_date;
+		view->prompt =
+		    (s->sort_by_date ? "Sort by date" : "Sort by name");
 		view->count = 0;
 		err = got_reflist_sort(&tog_refs, s->sort_by_date ?
 		    got_ref_cmp_by_commit_timestamp_descending :