An easy way to add multiple filters encoded in a single string. Filters are separated by '|' (bar character). Each filter has a name, separated from patterns list also by '|'. If filter name starts with '*', it's set as a default filter. Patterns are separated by ';' (semicolon character).
As you can see, this prevents some special characters from appearing in names and patterns. For maximum flexibility, don't use this function, use AddFilter.
For example All files (*)|*|All images (*.png;*.jpg)|*.png;*.jpg|PNG images (*.png)|*.png
Not finished pairs of name + pattern at the end of the string are ignored. In particular, empty string is unfinished (actually, it contains an empty Name, and is unfinished because there is no |, so no matching Pattern) so empty string causes no filters to be added.