Add support for opening multiple selected files from disk (#4128)

desktop/wrapper/src/intercept_frontend_message.rs

@@ -14,6 +14,7 @@ pub(super) fn intercept_frontend_message(dispatcher: &mut DesktopWrapperMessageD
 			dispatcher.respond(DesktopFrontendMessage::OpenFileDialog {
 				title: "Open Document".to_string(),
 				filters: vec![],
+				multiple: true,
 				context: OpenFileDialogContext::Open,
 			});
 		}
@@ -21,6 +22,7 @@ pub(super) fn intercept_frontend_message(dispatcher: &mut DesktopWrapperMessageD
 			dispatcher.respond(DesktopFrontendMessage::OpenFileDialog {
 				title: "Import File".to_string(),
 				filters: vec![],
+				multiple: false,
 				context: OpenFileDialogContext::Import,
 			});
 		}

desktop/wrapper/src/messages.rs

@@ -16,6 +16,7 @@ pub enum DesktopFrontendMessage {
 	OpenFileDialog {
 		title: String,
 		filters: Vec<FileFilter>,
+		multiple: bool,
 		context: OpenFileDialogContext,
 	},
 	SaveFileDialog {
@@ -102,6 +103,7 @@ pub struct FileFilter {
 	pub extensions: Vec<String>,
 }
 
+#[derive(Clone, Copy)]
 pub enum OpenFileDialogContext {
 	Open,
 	Import,