diff --git a/runelite-client/src/main/java/net/runelite/client/ui/ClientUI.java b/runelite-client/src/main/java/net/runelite/client/ui/ClientUI.java
index 81cf6a82ee..fbe616c79d 100644
--- a/runelite-client/src/main/java/net/runelite/client/ui/ClientUI.java
+++ b/runelite-client/src/main/java/net/runelite/client/ui/ClientUI.java
@@ -36,6 +36,7 @@ import java.awt.Dimension;
 import java.awt.Frame;
 import java.awt.Graphics;
 import java.awt.LayoutManager;
+import java.awt.Toolkit;
 import java.awt.TrayIcon;
 import java.awt.image.BufferedImage;
 import java.io.IOException;
@@ -53,7 +54,6 @@ import javax.swing.SwingUtilities;
 import lombok.Getter;
 import lombok.extern.slf4j.Slf4j;
 import net.runelite.api.Client;
-import net.runelite.api.Constants;
 import net.runelite.api.GameState;
 import net.runelite.api.Point;
 import net.runelite.api.events.ConfigChanged;
@@ -110,14 +110,12 @@ public class ClientUI
 	private final EventBus eventBus;
 	private Applet client;
 	private JFrame frame;
-	private JPanel container;
 	private JPanel navContainer;
 	private PluginPanel pluginPanel;
 	private ClientPluginToolbar pluginToolbar;
 	private ClientTitleToolbar titleToolbar;
 	private JButton currentButton;
 	private NavigationButton currentNavButton;
-	private int lastSize;
 
 	@Inject
 	private ClientUI(
@@ -186,17 +184,6 @@ public class ClientUI
 				height = 2160;
 			}
 
-			// Set minimum size to fixed mode size
-			if (width < Constants.GAME_FIXED_WIDTH)
-			{
-				width = Constants.GAME_FIXED_WIDTH;
-			}
-
-			if (height < Constants.GAME_FIXED_HEIGHT)
-			{
-				height = Constants.GAME_FIXED_HEIGHT;
-			}
-
 			final Dimension size = new Dimension(width, height);
 
 			client.setSize(size);
@@ -327,19 +314,19 @@ public class ClientUI
 			frame.setLocationRelativeTo(frame.getOwner());
 			frame.setResizable(true);
 
-			// Add close callback
 			SwingUtil.addGracefulExitCallback(frame, runelite::shutdown,
 				() -> client != null
 					&& client instanceof Client
 					&& ((Client) client).getGameState() != GameState.LOGIN_SCREEN);
 
-			container = new JPanel();
+			final JPanel container = new JPanel();
 			container.setLayout(new BoxLayout(container, BoxLayout.X_AXIS));
 			container.add(new ClientPanel(client));
 
-			navContainer = new JPanel(new BorderLayout(0, 0));
+			navContainer = new JPanel();
+			navContainer.setLayout(new BorderLayout(0, 0));
 			navContainer.setMinimumSize(new Dimension(0, 0));
-			navContainer.setMaximumSize(new Dimension(0, 0));
+			navContainer.setMaximumSize(new Dimension(0, Integer.MAX_VALUE));
 			container.add(navContainer);
 
 			pluginToolbar = new ClientPluginToolbar();
@@ -410,18 +397,8 @@ public class ClientUI
 				});
 			}
 
-			// If the window is restored from being maximized, restore also previous state properly
-			frame.addWindowStateListener(e ->
-			{
-				if ((e.getOldState() & Frame.MAXIMIZED_BOTH) == Frame.MAXIMIZED_BOTH)
-				{
-					revalidateSize(true);
-					frame.setLocationRelativeTo(frame.getOwner());
-				}
-			});
-
 			frame.pack();
-			revalidateSize(false);
+			SwingUtil.revalidateMinimumSize(frame);
 			frame.setLocationRelativeTo(frame.getOwner());
 			frame.setVisible(true);
 			frame.toFront();
@@ -505,66 +482,60 @@ public class ClientUI
 
 	private void expand(PluginPanel panel)
 	{
-		// Save last size
-		if ((frame.getExtendedState() & Frame.MAXIMIZED_BOTH) != Frame.MAXIMIZED_BOTH)
-		{
-			lastSize = frame.getWidth();
-		}
-
-		// We are switching panels, remove previous one
 		if (pluginPanel != null)
 		{
-			navContainer.remove(pluginPanel.getWrappedPanel());
+			navContainer.remove(0);
+		}
+		else
+		{
+			if (SwingUtil.isInScreenBounds(
+				frame.getLocationOnScreen().y + frame.getWidth() + PANEL_EXPANDED_WIDTH,
+				frame.getLocationOnScreen().y))
+			{
+				frame.setSize(frame.getWidth() + PANEL_EXPANDED_WIDTH, frame.getHeight());
+			}
 		}
 
-		// Expand navigation container
+		pluginPanel = panel;
 		navContainer.setMinimumSize(new Dimension(PANEL_EXPANDED_WIDTH, 0));
 		navContainer.setMaximumSize(new Dimension(PANEL_EXPANDED_WIDTH, Integer.MAX_VALUE));
 
-		// Add plugin panel to container
-		pluginPanel = panel;
-		final JPanel wrappedPanel = pluginPanel.getWrappedPanel();
+		final JPanel wrappedPanel = panel.getWrappedPanel();
 		navContainer.add(wrappedPanel);
 		navContainer.revalidate();
 
 		// panel.onActivate has to go after giveClientFocus so it can get focus if it needs.
 		giveClientFocus();
-		pluginPanel.onActivate();
+		panel.onActivate();
+
 		wrappedPanel.repaint();
-		revalidateSize(false);
+		SwingUtil.revalidateMinimumSize(frame);
 	}
 
 	private void contract()
 	{
-		// Remove plugin panel from nav container
+		boolean wasMinimumWidth = frame.getWidth() == frame.getMinimumSize().width;
 		pluginPanel.onDeactivate();
-		navContainer.remove(pluginPanel.getWrappedPanel());
-		pluginPanel = null;
-
-		// Hide nav container
+		navContainer.remove(0);
 		navContainer.setMinimumSize(new Dimension(0, 0));
 		navContainer.setMaximumSize(new Dimension(0, 0));
 		navContainer.revalidate();
-
-		// Give back focus
 		giveClientFocus();
-		revalidateSize(false);
-	}
+		SwingUtil.revalidateMinimumSize(frame);
 
-	private void revalidateSize(boolean force)
-	{
-		final int diff = frame.getWidth() - container.getWidth();
-		final int threshold = diff + Constants.GAME_FIXED_WIDTH + PANEL_EXPANDED_WIDTH + pluginToolbar.getWidth();
-		final Dimension dimension = frame.getLayout().minimumLayoutSize(frame);
-
-		// The JFrame only respects minimumSize if it was set by setMinimumSize
-		frame.setMinimumSize(dimension);
-
-		// If the frame size is under threshold, restore previous size
-		if (force || frame.getWidth() <= threshold)
+		if ((frame.getExtendedState() & Frame.MAXIMIZED_BOTH) != Frame.MAXIMIZED_BOTH)
 		{
-			frame.setSize(lastSize, 0);
+			if (wasMinimumWidth)
+			{
+				frame.setSize(frame.getMinimumSize().width, frame.getHeight());
+			}
+			else if (frame.getWidth() < Toolkit.getDefaultToolkit().getScreenSize().getWidth())
+			{
+				frame.setSize(frame.getWidth() - PANEL_EXPANDED_WIDTH, frame.getHeight());
+			}
 		}
+
+		pluginPanel = null;
 	}
 
 	private void giveClientFocus()
diff --git a/runelite-client/src/main/java/net/runelite/client/util/SwingUtil.java b/runelite-client/src/main/java/net/runelite/client/util/SwingUtil.java
index ff5015917e..05fee3993b 100644
--- a/runelite-client/src/main/java/net/runelite/client/util/SwingUtil.java
+++ b/runelite-client/src/main/java/net/runelite/client/util/SwingUtil.java
@@ -228,6 +228,17 @@ public class SwingUtil
 		});
 	}
 
+	/**
+	 * Revalidate minimum frame size.
+	 *
+	 * @param frame the frame
+	 */
+	public static void revalidateMinimumSize(final JFrame frame)
+	{
+		// The JFrame only respects minimumSize if it was set by setMinimumSize, for some reason. (atleast on windows/native)
+		frame.setMinimumSize(frame.getLayout().minimumLayoutSize(frame));
+	}
+
 	private static BufferedImage resizeImage(BufferedImage image, int newWidth, int newHeight)
 	{
 		final Image tmp = image.getScaledInstance(newWidth, newHeight, Image.SCALE_SMOOTH);