Save As for User Defined Language does not add filename extension

[robvanharrevelt]

If you edit a file with a non-standard filename extension for which you have defined a User Defined Language, then it would be convenient if that extension is automatically added when you save the document with a different name using "Save As".

Description of the Issue

If you edit a file with selected User Defined Language and save the document with a different name using "SaveAs", then the file is by default saved with type "All types", for which no extension is added. You can select other file types in the Save As dialog, but not the file type for the User Defined Language. If would be useful if you could also select the User Defined Language as file type, so that the file would be saved with the extension for that User Defined Language.

Steps to Reproduce the Issue

1. Open the User Defined Language dialog (Language -> User Defined Language -> Define your language)
2. Press the "Create New" button. Specify a name (.e.g. "test"), specify an extension in text field .Ext (.e.g. "xxx") and close the dialog.
3. Create a new file (File -> New). Set the Language of the file to "test" (Language -> test)
4. Then use File -> SaveAs
5. Enter a file name without extension (e.g. "test")
6. Press the "Save" button.

Expected Behavior

In the Save As dialog, the list for "Save as type" includes something like "User Defined Language - test (.xxx)" . And this type is selected by default in this case, because the Language was set to User Defined Language "test".

When the file is saved, the extension for User Defined language "test" ("xxx") is added to the file name, so the name of the saved file is test.xxx.

Actual Behavior

The User Defined Language "test" does not appear in the possible file types. File type "All types" has been selected.

The file is saved without filename extension (the filename is just test).

Debug Information

Notepad++ v7.8.8 (64-bit)
Build time : Jun 23 2020 - 23:59:56
Path : C:\Program Files\Notepad++\notepad++.exe
Admin mode : OFF
Local Conf mode : OFF
OS Name : Windows Server 2012 R2 Datacenter (64-bit)
OS Build : 9600.19676
Current ANSI codepage : 1252
Plugins : mimeTools.dll NppConverter.dll NppExport.dll