Improve the "file has been changed" dialog

[AlexTugarev]

• the title is too long
• the buttons should be something like Replace | Keep | Cancel

[AlexTugarev]

Thanks for the pointer @akosyakov!

Looking at what happened behind the scene, I think this also unveils a flaw with the integration of preferences in the plugin system. I get this message every time I'm switching the Python interpreter.

[akosyakov]

@AlexTugarev Can you file an issue for it with steps to reproduce?

[vince-fugnitto]

@kaiyue0329 I think this might be an interesting issue to take a look at, if you require any assistance (ex: how to reproduce) please let me know :)

[kaiyue0329]

@vince-fugnitto I re-formatted the file name so that only the only the last part of the path (ex. 'settings.json') is displayed in the title. I was wondering if you can help me to reproduce the issue. Thanks.

[vince-fugnitto]

@vince-fugnitto I re-formatted the file name so that only the only the last part of the path (ex. 'settings.json') is displayed in the title. I was wondering if you can help me to reproduce the issue. Thanks.

Unfortunately, I was unable to successfully reproduce the issue:

• I turned the preference auto safe off
• I made unsaved changes to a file
• I made updates on the filesystem for the same file
• I attempted to save the file, and while the save failed the dialog did not appear

Perhaps @AlexTugarev can help steps to reproduce.

[vince-fugnitto]

I managed to reproduce it following the same issue as #6786
Basically the idea is to add themes as plugins into the application, trigger the color theme command, and quickly change themes and eventually the problem occurs:

Steps:

1. create a plugins folder at the root of the application (mkdir plugins)
2. add themes to the plugins folder (copy them as .vsix files):
   • https://github.com/theia-ide/vscode-builtin-extensions/releases/download/v1.39.1-prel/theme-defaults-1.39.1-prel.vsix
   • https://github.com/theia-ide/vscode-builtin-extensions/releases/download/v1.39.1-prel/theme-monokai-1.39.1-prel.vsix
   • https://github.com/theia-ide/vscode-builtin-extensions/releases/download/v1.39.1-prel/theme-abyss-1.39.1-prel.vsix
3. trigger the command color theme ctrlcmd+shift+p and Preferences: Color Theme
4. toggle between the available themes (keeping the quick-open open), and eventually the dialog will pop up