Bug #53727 Tried to manage security on an instance and got the below error.
Submitted: 18 May 2010 6:56 Modified: 18 Jun 2010 13:24
Reporter: Adrian Cave Email Updates:
Status: No Feedback Impact on me:
None 
Category:MySQL Workbench Severity:S3 (Non-critical)
Version:5.2.16 OSS OS:Microsoft Windows
Assigned to: CPU Architecture:Any

[18 May 2010 6:56] Adrian Cave
Description:
Exception = System.Runtime.InteropServices.SEHException
Message = External component has thrown an exception.
FullText = System.Runtime.InteropServices.SEHException: External component has thrown an exception.
   at MySQL.Forms.DrawBoxImpl.drawbox_mouse_click(Object sender, MouseEventArgs e)
   at System.Windows.Forms.Control.OnMouseClick(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

How to repeat:
In main window, select Manage Security, Select the instance you want to manage, click OK. Error occurs
[18 May 2010 12:23] Johannes Taxacher
please try with most recent version
[18 May 2010 12:25] Adrian Cave
This apparently is the latest version. Downloaded yesterday. Can you show me otherwise?
[18 May 2010 13:24] Valeriy Kravchuk
Latest version is 5.2.21. You can get it from http://dev.mysql.com/downloads/workbench/5.2.html.
[18 Jun 2010 23:00] Bugs System
No feedback was provided for this bug for over a month, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
the status of the bug back to "Open".