A File Browser Control (client side only) is supported by BR:
OPEN #99: "NAME= OPEN|SAVE:starting-directory[mask], ..."
Specify OPEN or SAVE to indicate what style of file selection box should be used. The colon is required. If you wish to use the current directory as a starting point, use a period. (e.g. OPEN:. ) The mask is a wildcard filename mask that may contain question marks and asterisks. For example:
OPEN #99: "NAME= OPEN:.[*.PRL],SHR",INTERNAL,INPUT,RELATIVE
Available as of 4.18a.