Enable import button only if entry selected (#4761)

CHANGELOG.md

@@ -58,6 +58,7 @@ We refer to [GitHub issues](https://github.com/JabRef/jabref/issues) by using `#
 - We grouped the toolbar icons and changed the Open Library and Copy icons. [#4584](https://github.com/JabRef/jabref/issues/4584) 
 - We added a browse button next to the path text field for aux-based groups. [#4586](https://github.com/JabRef/jabref/issues/4586)
 - We changed the title of Group Dialog to "Add subgroup" from "Edit group" when we select Add subgroup option.
+- We enable import button only if entries are selected. [#4755](https://github.com/JabRef/jabref/issues/4755)
 - We made modifications to improve contrast of UI elements. [#4583](https://github.com/JabRef/jabref/issues/4583)
 
 ### Fixed

src/main/java/org/jabref/gui/importer/ImportEntriesDialog.java

@@ -5,6 +5,8 @@
 import javax.inject.Inject;
 import javax.swing.undo.UndoManager;
 
+import javafx.beans.binding.Bindings;
+import javafx.beans.binding.BooleanBinding;
 import javafx.css.PseudoClass;
 import javafx.fxml.FXML;
 import javafx.scene.Node;
@@ -61,6 +63,10 @@ public ImportEntriesDialog(BibDatabaseContext database, BackgroundTask<List<BibE
                   .load()
                   .setAsDialogPane(this);
 
+        BooleanBinding booleanBind = Bindings.isEmpty(entriesListView.getCheckModel().getCheckedItems());
+        Button btn = (Button) this.getDialogPane().lookupButton(importButton);
+        btn.disableProperty().bind(booleanBind);
+
         setResultConverter(button -> {
             if (button == importButton) {
                 viewModel.importEntries(entriesListView.getCheckModel().getCheckedItems());