diff --git a/README.md b/README.md
index 862217fd..5b4ab78a 100644
--- a/README.md
+++ b/README.md
@@ -40,3 +40,5 @@ http://codemetropolis.github.io/CodeMetropolis/
 1. navigate to `sources` folder
 1. `mvn clean package`
 1. The current distribution will be aviable under `source/distro`.
+
+## Demo
\ No newline at end of file
diff --git a/sources/gui/src/main/java/codemetropolis/toolchain/gui/CodeMetropolisGUI.java b/sources/gui/src/main/java/codemetropolis/toolchain/gui/CodeMetropolisGUI.java
index 7ef2ae8a..f331f813 100644
--- a/sources/gui/src/main/java/codemetropolis/toolchain/gui/CodeMetropolisGUI.java
+++ b/sources/gui/src/main/java/codemetropolis/toolchain/gui/CodeMetropolisGUI.java
@@ -6,8 +6,13 @@
 import java.awt.Image;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
+import java.awt.event.FocusEvent;
+import java.awt.event.FocusListener;
 import java.io.File;
 import java.io.PipedOutputStream;
+import java.nio.file.Files;
+import java.nio.file.InvalidPathException;
+import java.nio.file.Paths;
 import java.util.Random;
 
 import javax.swing.ImageIcon;
@@ -58,6 +63,9 @@ public class CodeMetropolisGUI extends JFrame {
   private CMSpinner scaleSpinner;
   private CMComboBox<LayoutAlgorithm> layoutSelector;
 
+  private static final Color colorGreen = Color.decode(Translations.t("color_green"));
+  private static final Color colorRed = Color.decode(Translations.t("color_red"));
+
   /**
    * Instantiates the CodeMetropolis GUI.
    *
@@ -96,6 +104,52 @@ public void initFields() {
     }
   }
 
+  public boolean validatePath(String path) {
+    if (path.isEmpty())
+      return false;
+    try {
+      return Files.exists(Paths.get(path));
+    } catch (InvalidPathException | NullPointerException ex) {
+      return false;
+    }
+  }
+
+  /**
+   * Function for checking the mapping path field, if the file is correct, the field turns green, otherwise it turns red.
+   *
+   * @return Return with focuslistener.
+   */
+  public FocusListener getFocusListener() {
+    FocusListener focusListener = new FocusListener() {
+      public void focusGained(FocusEvent e) {
+        try {
+          mappingPath = (CMTextField) e.getSource();
+          if(!(validatePath(mappingPath.getText()) && (mappingPath.getText().endsWith(".xml"))) || mappingPath.getText().isEmpty()) {
+            mappingPath.setBackground(colorRed);
+          } else {
+            mappingPath.setBackground(colorGreen);
+          }
+        } catch (ClassCastException ignored) {
+          GuiUtils.showError(Translations.t("gui_err_unexpected_err"));
+        }
+      }
+
+      public void focusLost(FocusEvent e) {
+        try {
+          mappingPath = (CMTextField) e.getSource();
+          if(!(validatePath(mappingPath.getText()) && (mappingPath.getText().endsWith(".xml"))) || mappingPath.getText().isEmpty()) {
+            mappingPath.setBackground(colorRed);
+          } else {
+            mappingPath.setBackground(colorGreen);
+          }
+        } catch (ClassCastException ignored) {
+          GuiUtils.showError(Translations.t("gui_err_unexpected_err"));
+        }
+      }
+    };
+    return focusListener;
+  }
+
   /**
    * Creates the base panel for the CodeMetropolis GUI.
    *
@@ -202,6 +256,7 @@ private final void addMappingOptions(JPanel panel) {
     mappingPath = new CMTextField(145, 555, 235, 30);
     CMButton mappingBrowse = new CMButton(Translations.t("gui_b_browse"), 385, 555, 100, 30);
     mappingBrowse.addActionListener(new BrowseListener(mappingPath, JFileChooser.FILES_ONLY, XML_FILTER));
+    mappingPath.addFocusListener(getFocusListener());
 
     CMLabel scaleLabel = new CMLabel(Translations.t("gui_l_scale"), 15, 590, 120, 30);
     scaleSpinner = new CMSpinner(145, 590, 120, 30);
diff --git a/sources/gui/src/main/java/codemetropolis/toolchain/gui/components/listeners/BrowseListener.java b/sources/gui/src/main/java/codemetropolis/toolchain/gui/components/listeners/BrowseListener.java
index 9e4776d7..49cce755 100644
--- a/sources/gui/src/main/java/codemetropolis/toolchain/gui/components/listeners/BrowseListener.java
+++ b/sources/gui/src/main/java/codemetropolis/toolchain/gui/components/listeners/BrowseListener.java
@@ -40,6 +40,7 @@ public BrowseListener(CMTextField fileNameTextField, int fileSelectionMode, File
   public void actionPerformed(ActionEvent event) {
     if (fileChooser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION) {
       fileNameTextField.setText(fileChooser.getSelectedFile().getAbsolutePath());
+      fileNameTextField.requestFocus();
     }
   }
 
diff --git a/sources/gui/src/main/resources/translations.properties b/sources/gui/src/main/resources/translations.properties
index f56865a2..b7f61c03 100644
--- a/sources/gui/src/main/resources/translations.properties
+++ b/sources/gui/src/main/resources/translations.properties
@@ -61,3 +61,7 @@ gui_err_sm_run_failed = Failed to run SourceMeter!
 gui_err_unexpected_err = Unexpected error occured!
 gui_err_unhandled_metric_source = Unhandled metric source!
 gui_err_world_gen_failed = World generation failed! Check logs for details!
+
+# Colors
+color_green = 0xA5FFB4
+color_red = 0xFF9C9C