draw crop handles (they don't do anything yet)

Program.cs

@@ -637,6 +637,7 @@ public class Game : GameWindow {
     // string[] files = Directory.GetFiles(@"c:\users\colin\pictures\photos\2023\07\23\");
     // string[] files = Directory.GetFiles(@"G:\DCIM\100EOSR6\");
     // string[] files = Directory.GetFiles(@"c:\users\colin\desktop\totte-output\2023\07\31");
+    // string[] files = Directory.GetFiles(@"c:\users\colin\desktop\import");
     // string[] files = Directory.GetFiles(@"C:\Users\colin\Pictures\photos\2018\06\23");
     // string[] files = Directory.GetFiles(@"C:\Users\colin\Desktop\Germany all\104D7000");
     // string[] files = Directory.GetFiles(@"C:\Users\colin\Desktop\many-birds\");
@@ -838,6 +839,31 @@ public class Game : GameWindow {
     DrawFilledBox(new Box2i(right, top, geometry.PhotoBox.Max.X, bottom), shadeColor);
     DrawBox(new Box2i(left - 1, top - 1, right + 1, bottom + 1), 1, Color4.White);
     if (active) {
+      // handles
+      int handleThickness = 3;
+      int handleLength = 16;
+      // top-left
+      DrawFilledBox(new Box2i(left - handleThickness, top - handleThickness,
+                              left + handleLength, top), Color4.White);
+      DrawFilledBox(new Box2i(left - handleThickness, top - handleThickness,
+                              left, top + handleLength), Color4.White);
+      // top-right
+      DrawFilledBox(new Box2i(right - handleLength, top - handleThickness,
+                              right + handleThickness, top), Color4.White);
+      DrawFilledBox(new Box2i(right, top - handleThickness,
+                              right + handleThickness, top + handleLength), Color4.White);
+      // bottom-left
+      DrawFilledBox(new Box2i(left - handleThickness, bottom,
+                              left + handleLength, bottom + handleThickness), Color4.White);
+      DrawFilledBox(new Box2i(left - handleThickness, bottom - handleLength,
+                              left, bottom + handleThickness), Color4.White);
+      // bottom-right
+      DrawFilledBox(new Box2i(right - handleLength, bottom,
+                              right + handleThickness, bottom + handleThickness), Color4.White);
+      DrawFilledBox(new Box2i(right + handleThickness, bottom - handleLength,
+                              right, bottom + handleThickness), Color4.White);
+
+      // thirds
       DrawHorizontalLine(left, Util.Lerp(top, bottom, 1.0 / 3), right, Color4.White);
       DrawHorizontalLine(left, Util.Lerp(top, bottom, 2.0 / 3), right, Color4.White);
       DrawVerticalLine(Util.Lerp(left, right, 1.0 / 3), top, bottom, Color4.White);