Warn a user when a sequence opened contains incorrect characters

See e.g. the attached file. It contains '~' characters in the sequence. Therefore, the "All symbols" alphabet is applied to the sequence when it is opened in UGENE and some algorithms are not available to a user (e.g. ORFs).

A warning should pop up in this case. Maybe an option should be provided to the user to create a copy of the document with skipping/replacing unknown symbols.