FV - Rendering issue with MessageBox

Summary

There's an area below the message box's label that is not render correctly. (see image 1).

If we move the message box around, then we get image 2.

This issue only happen with the Unicode version of Free Vision. The ShortString version does not display this behavior.

System Information

• Operating system: Arch Linux + Windows 10
• Processor architecture: x86-64
• Compiler version: 3.3.1-14994-g6aa49038-dirty
• Device: Computer

Steps to reproduce

• Save the example code to a file (test.pas), then run fpc test.pas

Example Project

program test;

{$mode objFPC}
{$H+}

uses
  {$ifdef UNIX}cwstring, {$endif}UApp, UMsgBox, Objects;

var
  TestApp : TApplication;

begin
  TestApp.Init;
  MessageBox('A string', nil, mfOKButton);
  TestApp.Run;
  TestApp.Done;
end.

What is the current bug behavior?

• MessageBox has rendering issue.

What is the expected (correct) behavior?

• MessageBox renders correctly.