Custom desktop file creation is not compliant with the standard when spaces are involved in Exec (and maybe other reserved characters)

I discovered this will using the Albert launcher's applications plugin. When you create a custom launcher with the Menu editor, if that executable has spaces in the path, the created desktop file escapes it as so:

Exec=/path\\ with/spaces

But, the desktop file specification says:

Arguments may be quoted in whole. If an argument contains a reserved character the argument must be quoted. The rules for quoting of arguments is also applicable to the executable name or path of the executable program as provided.
[...] Reserved characters are space (" "), tab, newline, double quote, single quote ("'"), backslash character (""), greater-than sign (">"), less-than sign ("<"), tilde ("~"), vertical bar ("|"), ampersand ("&"), semicolon (";"), dollar sign ("$"), asterisk ("*"), question mark ("?"), hash mark ("#"), parenthesis ("(") and (")") and backtick character ("`").

So, the resulting file should actually have the following line:

Exec="/path with/spaces"

Related bug reports:

• https://github.com/albertlauncher/albert-plugin-applications/issues/13
• https://github.com/albertlauncher/albert/issues/1596

The issue does not name a source file or test. Start by locating the custom launcher or Menu editor code that writes desktop files, reproduce a path containing spaces, and compare its Exec output with the desktop-entry specification. Done means reserved characters in executable paths are represented using the required quoting and the behavior is covered by a regression test if the project has tests.