[PATCH] funny feature: make Alt+< and Alt+> scroll the help lines sideways

[Benno Schulenberg]

This allows the user to get reminders on the screen also for the
less common functions, without having to access the ^G help text.
---
 src/definitions.h |  2 ++
 src/global.c      | 34 +++++++++++++++++++++++++++++++---
 src/nano.c        |  8 ++++++++
 src/prototypes.h  |  3 +++
 src/winio.c       |  4 ++++
 5 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/src/definitions.h b/src/definitions.h
index 2ce72260..02ee08cf 100644
--- a/src/definitions.h
+++ b/src/definitions.h
@@ -111,6 +111,8 @@
 #define BLIND  FALSE
 #define VISIBLE  TRUE
 
+#define HELPLINE_ITEMS  (((COLS + 40) / 20) * 2)
+
 #define JUSTFIND   0
 #define REPLACING  1
 #define INREGION   2
diff --git a/src/global.c b/src/global.c
index 0e9b0618..066a28af 100644
--- a/src/global.c
+++ b/src/global.c
@@ -141,6 +141,11 @@ ssize_t stripe_column = 0;
                /* The column at which a vertical bar will be drawn. */
 #endif
 
+size_t entries_in_main = 2;
+               /* The total number of items in the main menu -- calculated 
later. */
+int show_from = 0;
+               /* Display help items in the main menu starting from this 
index. */
+
 linestruct *cutbuffer = NULL;
                /* The buffer where we store cut text. */
 linestruct *cutbottom = NULL;
@@ -470,7 +475,7 @@ const keystruct *first_sc_for(int menu, void (*func)(void))
 size_t shown_entries_for(int menu)
 {
        funcstruct *item = allfuncs;
-       size_t maximum = ((COLS + 40) / 20) * 2;
+       size_t maximum = HELPLINE_ITEMS;
        size_t count = 0;
 
        while (count < maximum && item != NULL) {
@@ -560,6 +565,29 @@ functionptrtype interpret(int *keycode)
 }
 #endif /* ENABLE_BROWSER || ENABLE_HELP */
 
+#ifndef NANO_TINY
+/* Make the "bar" of help items scroll to the left. */
+void roll_left(void)
+{
+       if (show_from > 0)
+               show_from -= HELPLINE_ITEMS;
+       else
+               show_from = entries_in_main - (entries_in_main % 
HELPLINE_ITEMS);
+
+       currmenu = MMOST;
+}
+
+/* Make the "bar" of help items scroll to the right. */
+void roll_right(void)
+{
+       show_from += HELPLINE_ITEMS;
+       if (show_from > entries_in_main)
+               show_from = 0;
+
+       currmenu = MMOST;
+}
+#endif
+
 /* These two tags are used elsewhere too, so they are global. */
 /* TRANSLATORS: Try to keep the next two strings at most 10 characters. */
 const char *exit_tag = N_("Exit");
@@ -1366,13 +1394,13 @@ void shortcut_init(void)
        add_to_sclist(MMAIN|MHELP, "M-=", 0, do_scroll_down, 0);
 #endif
 #ifdef ENABLE_MULTIBUFFER
-       add_to_sclist(MMAIN, "M-<", 0, switch_to_prev_buffer, 0);
        add_to_sclist(MMAIN, "M-,", 0, switch_to_prev_buffer, 0);
-       add_to_sclist(MMAIN, "M->", 0, switch_to_next_buffer, 0);
        add_to_sclist(MMAIN, "M-.", 0, switch_to_next_buffer, 0);
 #endif
        add_to_sclist(MMOST, "M-V", 0, do_verbatim_input, 0);
 #ifndef NANO_TINY
+       add_to_sclist(MMAIN, "M-<", 0, roll_left, 0);
+       add_to_sclist(MMAIN, "M->", 0, roll_right, 0);
        add_to_sclist(MMAIN, "M-T", 0, cut_till_eof, 0);
        add_to_sclist(MEXECUTE, "^V", 0, cut_till_eof, 0);
        add_to_sclist(MMAIN, "M-D", 0, do_wordlinechar_count, 0);
diff --git a/src/nano.c b/src/nano.c
index 3dd9f917..6af45c24 100644
--- a/src/nano.c
+++ b/src/nano.c
@@ -433,6 +433,13 @@ void window_init(void)
                keypad(bottomwin, TRUE);
        }
 
+       entries_in_main = 0;
+
+       /* Determine the total number of presentable items in the main menu. */
+       for (funcstruct *item = allfuncs; item != NULL; item = item->next)
+               if (item->menus & MMAIN)
+                       entries_in_main++;
+
 #ifdef ENABLED_WRAPORJUSTIFY
        /* Set up the wrapping point, accounting for screen width when 
negative. */
        if (COLS + fill < 0)
@@ -1048,6 +1055,7 @@ void regenerate_screen(void)
         * recreate the subwindows with their (new) sizes. */
        terminal_init();
        window_init();
+       show_from = 0;
 
        /* If we have an open buffer, redraw the contents of the subwindows. */
        if (openfile) {
diff --git a/src/prototypes.h b/src/prototypes.h
index 07f8f75e..44c8ba32 100644
--- a/src/prototypes.h
+++ b/src/prototypes.h
@@ -99,6 +99,9 @@ extern int *bardata;
 extern ssize_t stripe_column;
 #endif
 
+extern size_t entries_in_main;
+extern int show_from;
+
 extern linestruct *cutbuffer;
 extern linestruct *cutbottom;
 extern bool keep_cutbuffer;
diff --git a/src/winio.c b/src/winio.c
index 6984a247..b713db5f 100644
--- a/src/winio.c
+++ b/src/winio.c
@@ -2388,6 +2388,7 @@ void post_one_key(const char *keystroke, const char *tag, 
int width)
 void bottombars(int menu)
 {
        size_t index, number, itemwidth;
+       int skip = show_from;
        const keystruct *s;
        funcstruct *f;
 
@@ -2422,6 +2423,9 @@ void bottombars(int menu)
                if (s == NULL)
                        continue;
 
+               if (menu == MMAIN && skip-- > 0)
+                       continue;
+
                wmove(bottomwin, 1 + index % 2, (index / 2) * itemwidth);
 
                /* When the number is uneven, the penultimate item can be 
double wide. */
-- 
2.29.3