[Vala] multithreading -> weird behaviour on win(msys) and macOS

[Wolfgang Mauer <wolfgang mauer kabelmail de>]

I have a strange behavior between Ubuntu/MSYS and macOS
I have a output window (buildTextView) and i like to put all output from 
"spawn_async_with_pipes" to the end of the buffer.

With Linux everything works like expected with no errors/warnings but on 
Windows(10/MSYS64) and macOS it get lots of errors.

(valaDevelop.exe:2980): Gtk-CRITICAL **: 16:33:50.460: 
gtk_text_view_get_buffer: assertion 'GTK_IS_TEXT_VIEW (text_view)' failed
(valaDevelop.exe:2980): Gtk-CRITICAL **: 16:33:50.460: 
gtk_text_buffer_get_insert: assertion 'GTK_IS_TEXT_BUFFER (buffer)' failed
(valaDevelop.exe:2980): Gtk-CRITICAL **: 16:33:50.460: 
gtk_text_view_scroll_to_mark: assertion 'GTK_IS_TEXT_VIEW (text_view)' 
failed
(valaDevelop.exe:2980): Gtk-CRITICAL **: 16:33:50.460: 
gtk_text_view_get_buffer: assertion 'GTK_IS_TEXT_VIEW (text_view)' failed
(valaDevelop.exe:2980): Gtk-CRITICAL **: 16:33:50.460: 
gtk_text_buffer_insert_at_cursor: assertion 'GTK_IS_TEXT_BUFFER 
(buffer)' failed

Any idea ?


                Process.spawn_async_with_pipes (".",
                     spawn_args,
                     spawn_env,
                     SpawnFlags.SEARCH_PATH | 
SpawnFlags.DO_NOT_REAP_CHILD,
                     null,
                     out compiler_pid,
                     out compiler_input,
                     out compiler_output,
                     out compiler_error);

                // stdout:
                IOChannel compilerOutput = new IOChannel.unix_new 
(compiler_output);
                compilerOutput.add_watch (IOCondition.IN | 
IOCondition.HUP, (channel, condition) =>
                {
                    if (condition  == IOCondition.HUP)
                        return false;
                    try
                    {
                        string line;
                        channel.read_line (out line, null, null);
                        // Timeout with 0 goes to "UI-Thread" ?!
                        GLib.Timeout.add(0, () =>
                        {
buildTextView.buffer.insert_at_cursor(line, -1);
                            var mark = buildTextView.buffer.get_insert();
buildTextView.scroll_to_mark(mark, 0, true, 1, 1);
                        }
                    }
                    catch (IOChannelError e)
                    {
                        log (null, LogLevelFlags.LEVEL_ERROR, "%s", 
e.message);
                        return false;
                    }
                    catch (ConvertError e)
                    {
                        log (null, LogLevelFlags.LEVEL_ERROR, "%s", 
e.message);
                        return false;
                    }
                    catch (Error e)
                    {
                        log (null, LogLevelFlags.LEVEL_ERROR, "%s", 
e.message);
                        return true;
                    }
                    return true;
                });

Thanks for help
Wolfgang