Unescaped literal commas are not identified correctly

[Lexikos]

MsgBox, Hello, world!  ; old
MsgBox "Hello", "world!"  ; new (incorrect)
MsgBox "Hello, world!"  ; correct

For most commands, commas in the last parameter do not need to be escaped; i.e. they are automatically literal. The second number in each g_act entry indicates the maximum number of parameters.

However, MsgBox has special handling for comma, so:

• If the first apparent parameter (Options) does not have the % force-expression prefix and is not a positive integer such as 48 or empty, the command is treated as having maximum 1 parameter (all commas are literal).
• If the third apparent parameter (Text) has the % force-expression prefix, the command is treated as normal (maximum 4 parameters).
• If the fourth apparent parameter (Timeout) does not have the % force-expression prefix and is not a positive number such as 1.0 or empty, the command is treated as having maximum 3 parameters (so all commas in the third parameter are literal).

When there is an expression parameter, splitting the parameters correctly requires matching up (), [] and {} (i.e. any comma enclosed within them does not delimit command parameters).

MsgBox 48, Title, Text, 1.0  ; all commas are delimiters
MsgBox, , Title, Text,  ; as above
MsgBox % Options, Title, Text, % Timeout  ; as above
MsgBox 16,, Hello, world!  ; only the first two commas delimit parameters
MsgBox % Options,, Hello, world!  ; as above
MsgBox Options, Title, Text, Timeout  ; ignore the words, this is all just one Text parameter