Marked setContentView() as deprecated and made it throw an exception as it has no effect on a MaterialDialog.

library/src/main/java/com/afollestad/materialdialogs/DialogBase.java

@@ -4,6 +4,7 @@ import android.app.Dialog;
 import android.content.Context;
 import android.content.DialogInterface;
 import android.view.View;
+import android.view.ViewGroup;
 
 import com.afollestad.materialdialogs.internal.MDRootLayout;
 
@@ -42,4 +43,22 @@ class DialogBase extends Dialog implements DialogInterface.OnShowListener {
         if (mShowListener != null)
             mShowListener.onShow(dialog);
     }
+
+    @Override
+    @Deprecated
+    public void setContentView(int layoutResID) throws IllegalAccessError {
+        throw new IllegalAccessError("setContentView() is not supported in MaterialDialog. Specify a custom view in the Builder instead.");
+    }
+
+    @Override
+    @Deprecated
+    public void setContentView(View view) throws IllegalAccessError {
+        throw new IllegalAccessError("setContentView() is not supported in MaterialDialog. Specify a custom view in the Builder instead.");
+    }
+
+    @Override
+    @Deprecated
+    public void setContentView(View view, ViewGroup.LayoutParams params) throws IllegalAccessError {
+        throw new IllegalAccessError("setContentView() is not supported in MaterialDialog. Specify a custom view in the Builder instead.");
+    }
 }

library/src/main/java/com/afollestad/materialdialogs/MaterialDialog.java

@@ -1247,11 +1247,13 @@ public class MaterialDialog extends DialogBase implements
     }
 
     @UiThread
+    @Override
     public final void setTitle(@NonNull CharSequence newTitle) {
         title.setText(newTitle);
     }
 
     @UiThread
+    @Override
     public final void setTitle(@StringRes int newTitleRes) {
         setTitle(mBuilder.context.getString(newTitleRes));
     }