src/main/java/org/saturnclient/common/provider/SaturnProvider.java

@@ -28,6 +28,12 @@ public interface SaturnProvider {
      */
     public IdentifierRef getPlayerSkin();
 
+    /**
+     * Whether this version draws glass (the blurred game behind translucent
+     * panels), so screens needn't blur the whole background.
+     */
+    public boolean supportsGlass();
+
     /** Shows a warning toast. Safe to call from any thread. */
     public void showWarning(String title, String message);
 }

src/main/java/org/saturnclient/ui/PanelScreen.java

@@ -1,5 +1,6 @@
 package org.saturnclient.ui;
 
+import org.saturnclient.common.provider.Providers;
 import org.saturnclient.ui.components.Sidebar;
 import org.saturnclient.ui.elements.ImageTexture;
 import org.saturnclient.ui.elements.Panel;
@@ -38,6 +39,9 @@ public abstract class PanelScreen extends SaturnScreen {
 
     @Override
     public final void ui() {
+        // The panels are frosted themselves, so the rest of the game stays clear.
+        blurBackground = !Providers.saturn.supportsGlass();
+
         panelWidth = Math.min(MAX_WIDTH, width - MARGIN * 2 - Sidebar.WIDTH - GAP);
         panelHeight = Math.min(MAX_HEIGHT, height - MARGIN * 2);
 

src/main/java/org/saturnclient/ui/RenderScope.java

@@ -34,6 +34,14 @@ public interface RenderScope {
         if (color == 0)
             return;
 
+        drawTexture(getRoundedRectangle(width, height, radius), x, y, 0, 0, width, height, color);
+    }
+
+    /**
+     * The white rounded rectangle that {@link #drawRoundedRectangle} tints, as a
+     * cached texture.
+     */
+    default IdentifierRef getRoundedRectangle(int width, int height, int radius) {
         radius = Math.min(radius, width / 2);
         radius = Math.min(radius, height / 2);
 
@@ -42,7 +50,24 @@ public interface RenderScope {
                 width, height,
                 radius, radius);
 
-        drawSvgShape(rect, "rounded_" + width + "_" + height + "_" + radius, x, y, width, height, color);
+        return getSvgShape(rect, "rounded_" + width + "_" + height + "_" + radius, width, height);
+    }
+
+    /**
+     * Frosts a rounded rectangle for a translucent background to be drawn over:
+     * the game behind the screen, blurred, cut to exactly the shape
+     * {@link #drawRoundedRectangle} draws. Draws nothing on versions without
+     * glass.
+     */
+    default void drawGlass(int x, int y, int width, int height, int radius) {
+        drawGlass(getRoundedRectangle(width, height, radius), x, y, width, height);
+    }
+
+    /**
+     * Draws the blurred game behind the screen where {@code mask}, stretched
+     * over the area, is opaque.
+     */
+    default void drawGlass(IdentifierRef mask, int x, int y, int width, int height) {
     }
 
     /**
@@ -89,15 +114,22 @@ public interface RenderScope {
      * {@code color}.
      */
     private void drawSvgShape(String shape, String cacheKey, int x, int y, int width, int height, int color) {
+        drawTexture(getSvgShape(shape, cacheKey, width, height), x, y, 0, 0, width, height, color);
+    }
+
+    /**
+     * {@code shape} (SVG elements in a {@code width} x {@code height} canvas,
+     * drawn in white) rendered to a cached texture.
+     */
+    private IdentifierRef getSvgShape(String shape, String cacheKey, int width, int height) {
         String svg = String.format(
                 "<svg xmlns='http://www.w3.org/2000/svg' width='%d' height='%d'>%s</svg>",
                 width, height, shape);
 
         InputStream svgStream = new ByteArrayInputStream(svg.getBytes(StandardCharsets.UTF_8));
 
-        drawTexture(SvgTexture.getSvg(svgStream,
-                IdentifierRef.ofSaturn("textures/gui/tmp_rect/" + cacheKey),
-                width * 4, height * 4), x, y, 0, 0, width, height, color);
+        return SvgTexture.getSvg(svgStream, IdentifierRef.ofSaturn("textures/gui/tmp_rect/" + cacheKey),
+                width * 4, height * 4);
     }
 
     void drawBorder(int x, int y, int width, int height, int color);

src/main/java/org/saturnclient/ui/SaturnScreen.java

@@ -46,11 +46,11 @@ public abstract class SaturnScreen {
     }
 
     /**
-     * How much to blur the game behind this screen right now: the client's
-     * setting, faded in over the screen's first moments.
+     * How much to blur the game behind this screen and its glass right now: the
+     * client's setting, faded in over the screen's first moments.
      */
-    public int getBackgroundBlur() {
-        if (!blurBackground || start == null) {
+    public int getBlurRadius() {
+        if (start == null) {
             return 0;
         }
 
@@ -58,6 +58,14 @@ public abstract class SaturnScreen {
         return Math.round(Config.backgroundBlur.value * Math.min(elapsed / (float) BLUR_FADE_IN, 1f));
     }
 
+    /**
+     * How much to blur the whole game behind this screen right now, or 0 when it
+     * isn't.
+     */
+    public int getBackgroundBlur() {
+        return blurBackground ? getBlurRadius() : 0;
+    }
+
     /**
      * The GUI scale setting this screen follows; the menu scale unless the
      * screen is another kind.

src/main/java/org/saturnclient/ui/elements/Panel.java

@@ -6,7 +6,8 @@ import org.saturnclient.ui.ElementContext;
 import org.saturnclient.ui.RenderScope;
 
 /**
- * The translucent, outlined surface that screens lay their content on.
+ * The translucent, outlined surface that screens lay their content on,
+ * frosted over the game where glass is supported.
  */
 public class Panel extends Element {
 
@@ -16,6 +17,11 @@ public class Panel extends Element {
     }
 
     public static void drawBackground(RenderScope renderScope, int width, int height) {
+        // Frosted behind a background that isn't solid
+        if (Theme.getPanelBg() >>> 24 < 0xFF) {
+            renderScope.drawGlass(0, 0, width, height, Theme.BG_RADIUS.value);
+        }
+
         renderScope.drawRoundedRectangle(0, 0, width, height, Theme.BG_RADIUS.value, 1,
                 Theme.getPanelBg(), Theme.getBorder());
     }