Draw{Texture,Box}: allow passing in a different draw color

Program.cs

@@ -50,9 +50,10 @@ void main(void) {
 out vec4 outputColor;
 in vec2 texCoord;
 uniform sampler2D texture0;
+uniform vec4 color;
 
 void main() {
-    outputColor = texture(texture0, texCoord);
+    outputColor = texture(texture0, texCoord) * color;
 }";
 
     VertexShader = GL.CreateShader(ShaderType.VertexShader);
@@ -306,7 +307,7 @@ public class Game : GameWindow {
       Rectangle box = new Rectangle(windowWidth - thumbnailWidth, i * thumbnailHeight, thumbnailWidth, thumbnailHeight);
       DrawTexture(textures[i], box);
       if (i == textureIndex) {
-        DrawBox(box, 3);
+        DrawBox(box, 3, new Color4(1f, 1f, 0f, 1f));
       }
     }
 
@@ -314,17 +315,22 @@ public class Game : GameWindow {
   }
 
   void DrawTexture(Texture texture, Rectangle box) {
+    DrawTexture(texture, box, new Color4(1f, 1f, 1f, 1f));
+  }
+
+  void DrawTexture(Texture texture, Rectangle box, Color4 color) {
+    GL.Uniform4(shader.GetUniformLocation("color"), color.R, color.G, color.B, color.A);
     SetVertices(box.Left, box.Top, box.Width, box.Height);
     GL.BufferData(BufferTarget.ArrayBuffer, vertices.Length * sizeof(float), vertices, BufferUsageHint.DynamicDraw);
     GL.BindTexture(TextureTarget.Texture2D, texture.Handle);
     GL.DrawElements(PrimitiveType.Triangles, indices.Length, DrawElementsType.UnsignedInt, 0);
   }
 
-  void DrawBox(Rectangle box, int thickness) {
-    DrawTexture(TEXTURE_WHITE, new Rectangle(box.Left, box.Top, box.Width, thickness));
-    DrawTexture(TEXTURE_WHITE, new Rectangle(box.Left, box.Top, thickness, box.Height));
-    DrawTexture(TEXTURE_WHITE, new Rectangle(box.Left, box.Top + box.Height - thickness, box.Width, thickness));
-    DrawTexture(TEXTURE_WHITE, new Rectangle(box.Left + box.Width - thickness, box.Top, thickness, box.Height));
+  void DrawBox(Rectangle box, int thickness, Color4 color) {
+    DrawTexture(TEXTURE_WHITE, new Rectangle(box.Left, box.Top, box.Width, thickness), color);
+    DrawTexture(TEXTURE_WHITE, new Rectangle(box.Left, box.Top, thickness, box.Height), color);
+    DrawTexture(TEXTURE_WHITE, new Rectangle(box.Left, box.Top + box.Height - thickness, box.Width, thickness), color);
+    DrawTexture(TEXTURE_WHITE, new Rectangle(box.Left + box.Width - thickness, box.Top, thickness, box.Height), color);
   }
 
   protected override void OnResize(ResizeEventArgs e) {