Using undo with two windows and crash appears (regression)

[grofaty]

I have downloaded Pinta 1.8 development for Ubuntu 20.04 from
https://github.com/PintaProject/Pinta/actions/runs/450000006

1. Open new image.
2. Open another new image.
3. CTRL+A to select whole image.
4. CTRL+C to copy image.
5. CTRL+V to paste image (not logical, but do it).
6. Click on Undo many times so you get all actions in image two undone.
7. Click on image one tab.
8. Click Undo twice and crash appears with error:

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.
 ---> System.InvalidOperationException: Undo stack is empty
   at Pinta.Core.DocumentHistory.Undo()
   at Pinta.Core.EditActions.HandlerPintaCoreActionsEditUndoActivated(Object sender, EventArgs e)
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at System.Delegate.DynamicInvokeImpl(Object[] args)
   at GLib.Signal.ClosureInvokedCB(Object o, ClosureInvokedArgs args)
   at GLib.SignalClosure.MarshalCallback(IntPtr raw_closure, IntPtr return_val, UInt32 n_param_vals, IntPtr param_values, IntPtr invocation_hint, IntPtr marshal_data)

[grofaty (grofaty)]

Now I see, steps from including 3 and including 6 can be skipped and crash appears anyway.

[grofaty (grofaty)]

I retested on Pinta 1.7 and crash does not appear. In Pinta 1.7 first image does not magically get Undo button enabled on first image when you click on second image.

[Cameron White (cameronwhite91)]

This might be similar to some issues that were recently fixed in the layers pad in the GTK3 branch.

[Cameron White (cameronwhite91)]

Fixed by https://github.com/PintaProject/Pinta/pull/195

[grofaty (grofaty)]

I can confirm. It is fixed. Thanks. I tested on latest github gtk3v2 commit.