Fix #5615 side pane not remembering position (#5629)

CHANGELOG.md

@@ -62,6 +62,7 @@ We refer to [GitHub issues](https://github.com/JabRef/jabref/issues) by using `#
 - We fixed an issue where the merge dialog showed the wrong text colour in "Dark" mode [#5516](https://github.com/JabRef/jabref/issues/5516)
 - We fixed an issue where the author field was not correctly parsed during bibtex key-generation. [#5551](https://github.com/JabRef/jabref/issues/5551)
 - We fixed an issue where notifications where shown during autosave. [#5555](https://github.com/JabRef/jabref/issues/5555)
+- We fixed an issue where the side pane was not remembering its position. [#5615](https://github.com/JabRef/jabref/issues/5615)
 
 ### Removed
 

src/main/java/org/jabref/gui/JabRefFrame.java

@@ -410,7 +410,6 @@ private void initLayout() {
         head.setCenter(createToolbar());
         setTop(head);
 
-        SplitPane.setResizableWithParent(sidePane, Boolean.FALSE);
         splitPane.getItems().addAll(sidePane, tabbedPane);
 
         // We need to wait with setting the divider since it gets reset a few times during the initial set-up
@@ -423,6 +422,8 @@ public void changed(ObservableValue<? extends Boolean> observable, Boolean oldVa
 
                     EasyBind.subscribe(sidePane.visibleProperty(), visible -> {
                         if (visible) {
+                            // Run SplitPane.setResizableWithParent later to avoid miscalculation during initial layouting
+                            Platform.runLater(() -> SplitPane.setResizableWithParent(sidePane, Boolean.FALSE));
                             if (!splitPane.getItems().contains(sidePane)) {
                                 splitPane.getItems().add(0, sidePane);
                                 setDividerPosition();