diff --git a/graphicswin.cpp b/graphicswin.cpp
index b6d98db..b664461 100644
--- a/graphicswin.cpp
+++ b/graphicswin.cpp
@@ -649,17 +649,17 @@ void GraphicsWindow::MouseMoved(double x, double y, bool leftDown,
                 double theta = atan2(orig.mouse.y-p2.y, orig.mouse.x-p2.x);
                 theta -= atan2(y-p2.y, x-p2.x);
 
-                Vector normal = orig.projRight.Cross(orig.projUp);
+                Vector normal = projRight.Cross(projUp);
                 u = u.RotatedAbout(normal, -theta);
                 v = v.RotatedAbout(normal, -theta);
             } else {
                 double dx = -(x - orig.mouse.x);
                 double dy = -(y - orig.mouse.y);
                 double s = 0.3*(PI/180); // degrees per pixel
-                u = u.RotatedAbout(orig.projUp, -s*dx);
-                u = u.RotatedAbout(orig.projRight, s*dy);
-                v = v.RotatedAbout(orig.projUp, -s*dx);
-                v = v.RotatedAbout(orig.projRight, s*dy);
+                u = u.RotatedAbout(projUp, -s*dx);
+                u = u.RotatedAbout(projRight, s*dy);
+                v = v.RotatedAbout(projUp, -s*dx);
+                v = v.RotatedAbout(projRight, s*dy);
             }
             orig.mouse = mp;
             normal->NormalForceTo(Quaternion::From(u, v));
diff --git a/polygon.cpp b/polygon.cpp
index 699b581..ded6ded 100644
--- a/polygon.cpp
+++ b/polygon.cpp
@@ -7,6 +7,10 @@ Vector STriangle::Normal(void) {
 
 bool STriangle::ContainsPoint(Vector p) {
     Vector n = Normal();
+    if(n.Magnitude() < LENGTH_EPS*LENGTH_EPS) {
+        // shouldn't happen; zero-area triangle
+        return false;
+    }
     return ContainsPointProjd(n.WithMagnitude(1), p);
 }
 
diff --git a/solvespace.cpp b/solvespace.cpp
index bb960f0..f3ce3b6 100644
--- a/solvespace.cpp
+++ b/solvespace.cpp
@@ -459,7 +459,7 @@ void SolveSpace::MenuFile(int id) {
 
         case GraphicsWindow::MNU_EXIT:
             if(!SS.OkayToStartNewFile()) break;
-            exit(0);
+            ExitNow();
             break;
 
         default: oops();
diff --git a/solvespace.h b/solvespace.h
index 121801d..b93038b 100644
--- a/solvespace.h
+++ b/solvespace.h
@@ -79,6 +79,7 @@ void dbp(char *str, ...);
         CO((tri).a), CO((tri).b), CO((tri).c))
 
 void Error(char *str, ...);
+void ExitNow(void);
 
 void *AllocTemporary(int n);
 void FreeAllTemporary(void);
diff --git a/win32/w32main.cpp b/win32/w32main.cpp
index 024e076..8eedc66 100644
--- a/win32/w32main.cpp
+++ b/win32/w32main.cpp
@@ -67,6 +67,10 @@ void Error(char *str, ...)
     MessageBox(h, buf, "SolveSpace Error", MB_OK | MB_ICONERROR);
 }
 
+void ExitNow(void) {
+    PostQuitMessage(0);
+}
+
 //-----------------------------------------------------------------------------
 // A separate heap, on which we allocate expressions. Maybe a bit faster,
 // since no fragmentation issues whatsoever, and it also makes it possible