signed ints, ignore negative -l value

dmenu.c

@@ -39,6 +39,10 @@ static void setup(void);
 static void usage(void);
 
 static char text[BUFSIZ];
+static int bh, mw, mh;
+static int inputw = 0;
+static int promptw;
+static int lines = 0;
 static size_t cursor = 0;
 static const char *font = NULL;
 static const char *prompt = NULL;
@@ -46,10 +50,6 @@ static const char *normbgcolor = "#cccccc";
 static const char *normfgcolor = "#000000";
 static const char *selbgcolor  = "#0066ff";
 static const char *selfgcolor  = "#ffffff";
-static unsigned int bh, mw, mh;
-static unsigned int inputw = 0;
-static unsigned int lines = 0;
-static unsigned int promptw;
 static unsigned long normcol[ColLast];
 static unsigned long selcol[ColLast];
 static Atom utf8;
@@ -444,6 +444,7 @@ setup(void) {
 
 	/* menu geometry */
 	bh = dc->font.height + 2;
+	lines = MAX(lines, 0);
 	mh = (lines + 1) * bh;
 #ifdef XINERAMA
 	if((info = XineramaQueryScreens(dc->dpy, &n))) {