Add key for toogling numlock handling

Keypad will generate keycodes when keypad application mode is enabled. It
can cause problems with some programs like vi, which operates in such
mode.

This patch change by default don't generate the keycodes never, but this
behaviour can be changed using the combination Alt + NumLock.
---
 config.def.h |   34 ++++++++++++++++++----------------
 st.c         |   17 +++++++++++++++--
 2 files changed, 33 insertions(+), 18 deletions(-)

1 files changed, 15 insertions, 2 deletions

diff --git a/st.c b/st.c
index 1647cbd..671b386 100644
--- a/st.c
+++ b/st.c
@@ -194,6 +194,7 @@ typedef struct {
 	int bot;	/* bottom scroll limit */
 	int mode;	/* terminal mode flags */
 	int esc;	/* escape state flags */
+	bool numlock;	/* lock numbers in keyboard */
 	bool *tabs;
 } Term;
 
@@ -261,6 +262,7 @@ typedef struct {
 /* function definitions used in config.h */
 static void xzoom(const Arg *);
 static void selpaste(const Arg *);
+static void numlock(const Arg *);
 
 /* Config.h for applying patches and the configuration. */
 #include "config.h"
@@ -1100,6 +1102,7 @@ tnew(int col, int row) {
 		term.alt [row] = xmalloc(term.col * sizeof(Glyph));
 		term.dirty[row] = 0;
 	}
+	term.numlock = 1;
 	memset(term.tabs, 0, term.col * sizeof(*term.tabs));
 	/* setup screen */
 	treset();
@@ -2700,6 +2703,12 @@ match(uint mask, uint state) {
 	return true;
 }
 
+void
+numlock(const Arg *dummy)
+{
+	term.numlock ^= 1;
+}
+
 char*
 kmap(KeySym k, uint state) {
 	uint mask;
@@ -2725,8 +2734,12 @@ kmap(KeySym k, uint state) {
 		if(!match(mask, state))
 			continue;
 
-		if((kp->appkey < 0 && IS_SET(MODE_APPKEYPAD)) ||
-				(kp->appkey > 0 && !IS_SET(MODE_APPKEYPAD))) {
+		if(kp->appkey > 0) {
+			if(!IS_SET(MODE_APPKEYPAD))
+				continue;
+			if(term.numlock && kp->appkey == 2)
+				continue;
+		} else if (kp->appkey < 0 && IS_SET(MODE_APPKEYPAD)) {
 			continue;
 		}