M config.arg.h → config.arg.h

@@ -19,6 +19,7 @@ #define STATUSFGCOLOR		"#9999cc"
 
 #define MASTER			600 /* per thousand */
 #define MODKEY			Mod1Mask
+#define SNAP			20 /* pixel */
 
 #define KEYS \
 static Key key[] = { \

M config.default.h → config.default.h

@@ -19,6 +19,7 @@ #define STATUSFGCOLOR		"#222222"
 
 #define MASTER			600 /* per thousand */
 #define MODKEY			Mod1Mask
+#define SNAP			20 /* pixel */
 
 #define KEYS \
 static Key key[] = { \

M event.c → event.c

@@ -48,6 +48,14 @@ case MotionNotify:
 			XSync(dpy, False);
 			c->x = ocx + (ev.xmotion.x - x1);
 			c->y = ocy + (ev.xmotion.y - y1);
+			if(abs(c->x) < sx + SNAP)
+				c->x = sx;
+			if(abs(c->y) < sy + bh + SNAP)
+				c->y = sy + bh;
+			if(abs(c->x + c->w) > sx + sw - SNAP)
+				c->x = sw - c->w - 2 * BORDERPX;
+			if(abs(c->y + c->h) > sy + sh - SNAP)
+				c->y = sh - c->h - 2 * BORDERPX;
 			resize(c, False, TopLeft);
 			break;
 		}