Chris,

I tried your fix, openbve-leezer3 and I got the following:

keithclark@keith:/usr/share/games/openbve/Plugins$ openbve-leezer3

(cli:31994): GLib-CRITICAL **: g_hash_table_insert_internal: assertion 'hash_table != NULL' failed
Stacktrace:

  at <unknown> <0xffffffff>
  at (wrapper managed-to-native) System.Drawing.GDIPlus.GdipLoadImageFromFile (string,intptr&) <0xffffffff>
  at System.Drawing.Image.FromFile (string,bool) <0x0005b>
  at System.Drawing.Image.FromFile (string) <0x00013>
  at OpenBve.formMain.LoadImage (string,string) <0x00053>
  at OpenBve.formMain.formMain_Load (object,System.EventArgs) <0x00b8b>
  at System.Windows.Forms.Form.OnLoad (System.EventArgs) <0x00075>
  at System.Windows.Forms.Form.OnLoadInternal (System.EventArgs) <0x0007f>
  at System.Windows.Forms.Form.OnCreateControl () <0x00053>
  at System.Windows.Forms.Control.CreateControl () <0x0011f>
  at System.Windows.Forms.Control.WmShowWindow (System.Windows.Forms.Message&) <0x00167>
  at System.Windows.Forms.Control.WndProc (System.Windows.Forms.Message&) <0x002d3>
  at System.Windows.Forms.ScrollableControl.WndProc (System.Windows.Forms.Message&) <0x0001b>
  at System.Windows.Forms.ContainerControl.WndProc (System.Windows.Forms.Message&) <0x0005b>
  at System.Windows.Forms.Form.WndProc (System.Windows.Forms.Message&) <0x00253>
  at System.Windows.Forms.Control/ControlWindowTarget.OnMessage (System.Windows.Forms.Message&) <0x00025>
  at System.Windows.Forms.Control/ControlNativeWindow.WndProc (System.Windows.Forms.Message&) <0x00036>
  at System.Windows.Forms.NativeWindow.WndProc (intptr,System.Windows.Forms.Msg,intptr,intptr) <0x00310>
  at System.Windows.Forms.XplatUIX11.SendMessage (intptr,System.Windows.Forms.Msg,intptr,intptr) <0x003f3>
  at System.Windows.Forms.XplatUIX11.MapWindow (System.Windows.Forms.Hwnd,System.Windows.Forms.WindowType) <0x001df>
  at System.Windows.Forms.XplatUIX11.CreateWindow (System.Windows.Forms.CreateParams) <0x00bab>
  at System.Windows.Forms.XplatUI.CreateWindow (System.Windows.Forms.CreateParams) <0x0001f>
  at System.Windows.Forms.NativeWindow.CreateHandle (System.Windows.Forms.CreateParams) <0x0003f>
  at System.Windows.Forms.Control.CreateHandle () <0x00069>
  at System.Windows.Forms.Form.CreateHandle () <0x0002b>
  at System.Windows.Forms.Control.CreateControl () <0x00087>
  at System.Windows.Forms.Control.SetVisibleCore (bool) <0x00083>
  at System.Windows.Forms.Form.SetVisibleCore (bool) <0x002ef>
  at System.Windows.Forms.Control.set_Visible (bool) <0x00032>
  at (wrapper remoting-invoke-with-check) System.Windows.Forms.Control.set_Visible (bool) <0xffffffff>
  at System.Windows.Forms.Application.RunLoop (bool,System.Windows.Forms.ApplicationContext) <0x002fb>
  at System.Windows.Forms.Form.ShowDialog (System.Windows.Forms.IWin32Window) <0x008ab>
  at System.Windows.Forms.Form.ShowDialog () <0x00013>
  at (wrapper remoting-invoke-with-check) System.Windows.Forms.Form.ShowDialog () <0xffffffff>
  at OpenBve.formMain.ShowMainDialog (OpenBve.formMain/MainDialogResult) <0x00307>
  at OpenBve.Program.Main (string[]) <0x00d73>
  at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object (object,intptr,intptr,intptr) <0xffffffff>

Native stacktrace:

	/usr/bin/cli() [0x4b73d8]
	/usr/bin/cli() [0x50f13b]
	/usr/bin/cli() [0x423d22]
	/lib/x86_64-linux-gnu/libpthread.so.0(+0x10340) [0x7f7d50bd9340]
	/usr/lib/libgdiplus.so.0(+0x415ca) [0x7f7d4d7445ca]
	/usr/lib/libgdiplus.so.0(GdipLoadImageFromFile+0x18a) [0x7f7d4d72767a]
	[0x40532802]

Debug info from gdb:

Could not attach to process.  If your uid matches the uid of the target
process, check the setting of /proc/sys/kernel/yama/ptrace_scope, or try
again as the root user.  For more details, see /etc/sysctl.d/10-ptrace.conf
ptrace: Operation not permitted.
No threads.

=================================================================
Got a SIGSEGV while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries 
used by your application.
=================================================================

Aborted (core dumped)