diff --git a/class.lua b/class.lua
index d578ae4..20319f0 100644
--- a/class.lua
+++ b/class.lua
@@ -51,7 +51,7 @@ end
 
 -- returns a deep copy of `other'
 local function clone(other)
-	return include({}, other)
+	return setmetatable(include({}, other), getmetatable(other))
 end
 
 local function new(class)
diff --git a/gamestate.lua b/gamestate.lua
index 854100c..c440180 100644
--- a/gamestate.lua
+++ b/gamestate.lua
@@ -36,6 +36,7 @@ function GS.new(t) return t or {} end -- constructor - deprecated!
 
 function GS.switch(to, ...)
 	assert(to, "Missing argument: Gamestate to switch to")
+	assert(to ~= GS, "Can't call switch with colon operator")
 	local pre = stack[#stack]
 	;(pre.leave or __NULL__)(pre)
 	;(to.init or __NULL__)(to)
@@ -46,6 +47,7 @@ end
 
 function GS.push(to, ...)
 	assert(to, "Missing argument: Gamestate to switch to")
+	assert(to ~= GS, "Can't call push with colon operator")
 	local pre = stack[#stack]
 	;(to.init or __NULL__)(to)
 	to.init = nil
@@ -53,11 +55,12 @@ function GS.push(to, ...)
 	return (to.enter or __NULL__)(to, pre, ...)
 end
 
-function GS.pop()
+function GS.pop(...)
 	assert(#stack > 1, "No more states to pop!")
 	local pre = stack[#stack]
 	stack[#stack] = nil
-	return (pre.leave or __NULL__)(pre)
+	;(pre.leave or __NULL__)(pre)
+	return (stack[#stack].resume or __NULL__)(pre, ...)
 end
 
 function GS.current()
diff --git a/signal.lua b/signal.lua
index 7cb246e..52b4d63 100644
--- a/signal.lua
+++ b/signal.lua
@@ -83,7 +83,7 @@ local default = new()
 
 return setmetatable({
 	new            = new,
-	register       = function(...) default:register(...) end,
+	register       = function(...) return default:register(...) end,
 	emit           = function(...) default:emit(...) end,
 	remove         = function(...) default:remove(...) end,
 	clear          = function(...) default:clear(...) end,
diff --git a/vector-light.lua b/vector-light.lua
index c352ebc..962c2c4 100644
--- a/vector-light.lua
+++ b/vector-light.lua
@@ -116,7 +116,7 @@ end
 -- ref.: http://blog.signalsondisplay.com/?p=336
 local function trim(maxLen, x, y)
 	local s = maxLen * maxLen / len2(x, y)
-	s = s < 1 and 1 or math.sqrt(s)
+	s = s > 1 and 1 or math.sqrt(s)
 	return x * s, y * s
 end
 
diff --git a/vector.lua b/vector.lua
index 0762ce5..9abdf34 100644
--- a/vector.lua
+++ b/vector.lua
@@ -36,7 +36,7 @@ end
 local zero = new(0,0)
 
 local function isvector(v)
-	return getmetatable(v) == vector
+	return type(v) == 'table' and type(v.x) == 'number' and type(v.y) == 'number'
 end
 
 function vector:clone()
@@ -169,16 +169,16 @@ end
 -- ref.: http://blog.signalsondisplay.com/?p=336
 function vector:trim_inplace(maxLen)
 	local s = maxLen * maxLen / self:len2()
-	s = s < 1 and 1 or math.sqrt(s)
+	s = (s > 1 and 1) or math.sqrt(s)
 	self.x, self.y = self.x * s, self.y * s
 	return self
 end
 
 function vector:angleTo(other)
 	if other then
-		return atan2(self.y, self.y) - atan2(other.y, other.x)
+		return atan2(self.y, self.x) - atan2(other.y, other.x)
 	end
-	return atan2(self.y, self.y)
+	return atan2(self.y, self.x)
 end
 
 function vector:trimmed(maxLen)