Convert PreferenceDialog to MVVM

src/main/java/org/jabref/gui/Base.css

@@ -1036,3 +1036,7 @@ We want to have a look that matches our icons in the tool-bar */
 .dialog-pane {
     -fx-background-color: -fx-control-inner-background;
 }
+
+.preference-sidepane {
+    -fx-background-color: -jr-sidepane-background;
+}

src/main/java/org/jabref/gui/preferences/ExternalTab.java

@@ -58,7 +58,7 @@ class ExternalTab implements PrefsTab {
     private final DialogService dialogService;
     private final FileDialogConfiguration fileDialogConfiguration = new FileDialogConfiguration.Builder().build();
 
-    public ExternalTab(JabRefFrame frame, PreferencesDialog prefsDiag, JabRefPreferences prefs) {
+    public ExternalTab(JabRefFrame frame, JabRefPreferences prefs) {
         this.prefs = prefs;
         this.frame = frame;
         dialogService = frame.getDialogService();

src/main/java/org/jabref/gui/preferences/FileTab.fxml

@@ -0,0 +1,84 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.scene.control.Button?>
+<?import javafx.scene.control.CheckBox?>
+<?import javafx.scene.control.ComboBox?>
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.control.RadioButton?>
+<?import javafx.scene.control.TextField?>
+<?import javafx.scene.control.ToggleGroup?>
+<?import javafx.scene.control.Tooltip?>
+<?import javafx.scene.layout.HBox?>
+<?import javafx.scene.layout.VBox?>
+
+<fx:root prefWidth="650.0" spacing="10.0" type="VBox"
+         xmlns="http://javafx.com/javafx/8.0.212" xmlns:fx="http://javafx.com/fxml/1"
+         fx:controller="org.jabref.gui.preferences.FileTabView">
+    <fx:define>
+        <ToggleGroup fx:id="stringsResolveToggleGroup"/>
+        <ToggleGroup fx:id="autolinkToggleGroup"/>
+    </fx:define>
+    <children>
+        <Label styleClass="sectionHeader" text="%General"/>
+        <CheckBox fx:id="openLastStartup" text="%Open last edited libraries at startup"/>
+        <CheckBox fx:id="backupOldFile" text="%Backup old file when saving"/>
+        <HBox alignment="CENTER_LEFT" spacing="10.0">
+            <children>
+                <Label text="%Do not wrap the following fields when saving"/>
+                <TextField fx:id="noWrapFiles" HBox.hgrow="ALWAYS"/>
+            </children>
+        </HBox>
+        <RadioButton fx:id="resolveStringsBibTex" text="%Resolve strings for standard BibTeX fields only"
+                     toggleGroup="$stringsResolveToggleGroup"/>
+        <HBox alignment="CENTER_LEFT" spacing="10.0">
+            <children>
+                <RadioButton fx:id="resolveStringsAll" alignment="TOP_LEFT" maxWidth="Infinity"
+                             text="%Resolve strings for all fields except" toggleGroup="$stringsResolveToggleGroup"/>
+                <TextField fx:id="resolveStringsExcept" disable="${!resolveStringsAll.selected}" HBox.hgrow="ALWAYS"/>
+            </children>
+        </HBox>
+        <HBox alignment="CENTER_LEFT" spacing="10.0">
+            <children>
+                <Label alignment="TOP_LEFT" text="%Newline separator"/>
+                <ComboBox fx:id="newLineSeparator" prefWidth="120.0"/>
+            </children>
+        </HBox>
+        <CheckBox fx:id="alwaysReformatBib" text="%Always reformat BIB file on save and export"/>
+        <Label styleClass="sectionHeader" text="%External file links"/>
+        <HBox alignment="CENTER_LEFT" spacing="10.0">
+            <children>
+                <Label text="%Main file directory"/>
+                <TextField fx:id="mainFileDir" HBox.hgrow="ALWAYS"/>
+                <Button onAction="#mainFileDirBrowse" text="%Browse"/>
+            </children>
+        </HBox>
+        <CheckBox fx:id="useBibLocationAsPrimary" text="%Use the BIB file location as primary file directory">
+            <tooltip>
+                <Tooltip
+                        text="%When downloading files, or moving linked files to the file directory, prefer the BIB file location rather than the file directory set above"/>
+            </tooltip>
+        </CheckBox>
+        <RadioButton fx:id="autolinkFileStartsBibtex" text="%Autolink files with names starting with the BibTeX key"
+                     toggleGroup="$autolinkToggleGroup"/>
+        <RadioButton fx:id="autolinkFileExactBibtex" text="%Autolink only files that match the BibTeX key"
+                     toggleGroup="$autolinkToggleGroup"/>
+        <HBox alignment="CENTER_LEFT" spacing="10.0">
+            <children>
+                <RadioButton fx:id="autolinkUseRegex" text="%Use regular expression search"
+                             toggleGroup="$autolinkToggleGroup"/>
+                <TextField fx:id="autolinkRegexKey" disable="${!autolinkUseRegex.selected}" HBox.hgrow="ALWAYS"/>
+                <Button fx:id="autolinkRegexHelp"/>
+            </children>
+        </HBox>
+        <CheckBox fx:id="searchFilesOnOpen"
+                  text="%When opening file link, search for matching file if no link is defined"/>
+        <CheckBox fx:id="openBrowseOnCreate" text="%Automatically open browse dialog when creating new file link"/>
+        <Label styleClass="sectionHeader" text="%Autosave"/>
+        <HBox alignment="CENTER_LEFT" spacing="10.0">
+            <children>
+                <CheckBox fx:id="autosaveLocalLibraries" text="%Autosave local libraries"/>
+                <Button fx:id="autosaveLocalLibrariesHelp"/>
+            </children>
+        </HBox>
+    </children>
+</fx:root>