fyne-ioGH-4595: add method to set view of filedialog

dialog/file.go

@@ -84,6 +84,8 @@ type FileDialog struct {
 	startingLocation fyne.ListableURI
 	// this will be the initial filename in a FileDialog in save mode
 	initialFileName string
+	// this will be the initial view in a FileDialog
+	initialView ViewLayout
 }
 
 // Declare conformity to Dialog interface
@@ -774,6 +776,17 @@ func (f *FileDialog) SetFileName(fileName string) {
 	}
 }
 
+// SetView changes the default display view of the FileDialog
+// This is normally called before the dialog is shown.
+//
+// Since: 2.5
+func (f *FileDialog) SetView(v ViewLayout) {
+	f.initialView = v
+	if f.dialog != nil {
+		f.dialog.setView(v)
+	}
+}
+
 // NewFileOpen creates a file dialog allowing the user to choose a file to open.
 // The callback function will run when the dialog closes. The URI will be nil
 // when the user cancels or when nothing is selected.