# Specification: Frosted Glass Background Effect (REPAIR - TRUE GPU)

## Overview
Implement a high-fidelity "frosted glass" (acrylic) background effect using a dedicated OpenGL pipeline. This implementation follows professional rendering patterns (downsampling, multi-pass blurring, and screen-space sampling) to ensure a smooth, milky look that remains performant on high-DPI displays.

## Functional Requirements
- **Dedicated Background Pipeline:**
  - Render the animated "Deep Sea" background shader to an off-screen `SceneFBO` once per frame.
- **Multi-Scale Downsampled Blur:**
  - Downsample the `SceneFBO` texture to 1/4 or 1/8 resolution.
  - Perform 2-pass Gaussian blurring on the downsampled texture to achieve a creamy "milky" aesthetic.
- **ImGui Panel Integration:**
  - Each ImGui panel must sample its background from the blurred texture using screen-space UV coordinates.
  - Automatically force window transparency (`alpha 0.0`) when the effect is active.
- **Real-Time Shader Tuning:**
  - Control blur radius, tint intensity, and opacity via the Live Shader Editor.
- **Stability:**
  - Balanced style-stack management to prevent ImGui assertion crashes.
  - Strict 1-space indentation and class scope protection.

## Technical Implementation
- **FBO Management:** Persistent FBOs for scene, temp, and blur textures.
- **UV Math:** `(window_pos / screen_res)` mapping to handle high-DPI scaling and vertical flipping.
- **DrawList Callbacks:** (If necessary) use callbacks to ensure the background is ready before panels draw.

## Acceptance Criteria
- [ ] Toggling the effect does not crash the app.
- [ ] Windows show a deep, high-quality blur of the background shader.
- [ ] Blur follows windows perfectly during drag/resize.
- [ ] The "Milky" look is highly visible even at low radii.