Allow adding and deleting multiple files in the general tab

Fixes #8659
Make @AEgit happy

CHANGELOG.md

@@ -31,6 +31,7 @@ Note that this project **does not** adhere to [Semantic Versioning](http://semve
 
 ### Fixed
 
+- We fixed an issue where it was no longer possible to add or delete multiple files in the `file` field in the entry editor [#8659](https://github.com/JabRef/jabref/issues/8659)
 - We fixed an issue where the author's lastname was not used for the citation key generation if it started with a lowercase letter [#8601](https://github.com/JabRef/jabref/issues/8601)
 - We fixed an issue where custom "Protected terms" files were missing after a restart of JabRef [#8608](https://github.com/JabRef/jabref/issues/8608)
 - We fixed an issue where JabRef could not start due to a missing directory for the fulltex index [#8579](https://github.com/JabRef/jabref/issues/8579)

src/main/java/org/jabref/gui/fieldeditors/LinkedFilesEditor.fxml

@@ -9,7 +9,7 @@
 <?import org.jabref.gui.icon.JabRefIconView?>
 <fx:root xmlns:fx="http://javafx.com/fxml/1" type="HBox" xmlns="http://javafx.com/javafx/8.0.112"
          fx:controller="org.jabref.gui.fieldeditors.LinkedFilesEditor">
-    <ListView fx:id="listView" prefHeight="0" HBox.hgrow="ALWAYS" maxHeight="100"/>
+    <ListView fx:id="listView" prefHeight="0" HBox.hgrow="ALWAYS" maxHeight="100" />
     <Button onAction="#addNewFile"
             styleClass="icon-button">
         <graphic>

src/main/java/org/jabref/gui/fieldeditors/LinkedFilesEditor.java

@@ -13,6 +13,7 @@
 import javafx.scene.control.ContextMenu;
 import javafx.scene.control.ListView;
 import javafx.scene.control.ProgressBar;
+import javafx.scene.control.SelectionMode;
 import javafx.scene.control.SeparatorMenuItem;
 import javafx.scene.control.Tooltip;
 import javafx.scene.input.ClipboardContent;
@@ -92,6 +93,7 @@ public LinkedFilesEditor(Field field,
                 .withValidation(LinkedFileViewModel::fileExistsValidationStatus);
 
         listView.setCellFactory(cellFactory);
+        listView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
 
         decoratedModelList = new UiThreadObservableList<>(viewModel.filesProperty());
         Bindings.bindContentBidirectional(listView.itemsProperty().get(), decoratedModelList);
@@ -204,8 +206,8 @@ private void setUpKeyBindings() {
             if (keyBinding.isPresent()) {
                 switch (keyBinding.get()) {
                     case DELETE_ENTRY:
-                        LinkedFileViewModel selectedItem = listView.getSelectionModel().getSelectedItem();
-                        if (selectedItem != null) {
+                        ObservableList<LinkedFileViewModel> selectedItems = listView.getSelectionModel().getSelectedItems();
+                        for (LinkedFileViewModel selectedItem : selectedItems) {
                             viewModel.deleteFile(selectedItem);
                         }
                         event.consume();

src/main/java/org/jabref/gui/fieldeditors/LinkedFilesEditorViewModel.java

@@ -144,7 +144,7 @@ public void addNewFile() {
                 .build();
 
         List<Path> fileDirectories = databaseContext.getFileDirectories(preferences.getFilePreferences());
-        dialogService.showFileOpenDialog(fileDialogConfiguration).ifPresent(newFile -> {
+        dialogService.showFileOpenDialogAndGetMultipleFiles(fileDialogConfiguration).forEach(newFile -> {
             LinkedFile newLinkedFile = fromFile(newFile, fileDirectories, externalFileTypes);
             files.add(new LinkedFileViewModel(
                     newLinkedFile,