change alpha

config.h

@@ -93,6 +93,9 @@ char *termname = "xterm-256color";
  */
 unsigned int tabspaces = 8;
 
+/* Background opacity */
+float alpha_def;
+
 /* bg opacity */
 float alpha = 0.8;
 
@@ -226,7 +229,9 @@ static Shortcut shortcuts[] = {
 	{ TERMMOD,              XK_Num_Lock,    numlock,        {.i =  0} },
     { ShiftMask,            XK_Page_Up,     kscrollup,      {.i = -1} },
     { ShiftMask,            XK_Page_Down,   kscrolldown,    {.i = -1} },
-
+    { MODKEY,               XK_bracketleft, chgalpha,       {.f = -1} }, /* Decrease opacity */
+	{ MODKEY,               XK_bracketright,  chgalpha,       {.f = +1} }, /* Increase opacity */
+	{ MODKEY|ShiftMask,     XK_braceright,chgalpha,       {.f =  0} }, /* Reset opacity */
 };
 
 /*