1 files changed, 13 insertions, 4 deletions
diff --git a/redo/dialog.go b/redo/dialog.go
index 877ccf2..1567cc7 100644
--- a/redo/dialog.go
+++ b/redo/dialog.go
@@ -2,10 +2,19 @@
 
 package ui
 
+type windowDialog interface {
+	openFile(f func(filename string))
+}
+
 // OpenFile opens a dialog box that asks the user to choose a file.
-// It returns the selected filename, or an empty string if no file was chosen.
-// All events stop while OpenFile is executing. (TODO move to doc.go)
+// The dialog box is modal to win, which mut not be nil.
+// Some time after the dialog box is closed, OpenFile runs f on the main thread, passing filename.
+// filename is the selected filename, or an empty string if no file was chosen.
+// OpenFile does not ensure that f remains alive; the programmer is responsible for this.
 // If possible on a given system, OpenFile() will not dereference links; it will return the link file itself.
-func OpenFile() (filename string) {
-	return openFile()
+func OpenFile(win Window, f func(filename string)) {
+	if win == nil {
+		panic("Window passed to OpenFile() cannot be nil")
+	}
+	win.openFile(f)
 }