fix: aggressive window refresh loop and focus-stealing on Windows

CHANGELOG.md

@@ -6,12 +6,15 @@
 > **Release Cadence Update:** Planned releases are shifting from weekly to fortnightly (targeting Wednesdays) as we transition toward a monthly release cycle. Critical fixes will still be released immediately as emergency patches.
 
 ### Plan
-- Aggressive window refresh loop and focus-stealing on Windows [#19]
 
 ### Added
 
 ### Fixed
 
+- Aggressive window refresh loop and focus-stealing on Windows [#19]
+- Legacy hardware (≤4 cores and ≤8 GiB RAM) falls back to software rendering on every platform, sidestepping the GPU/DWM recomposition loop behind the flicker
+- Software-rendering fallback uses Qt's `AA_UseSoftwareOpenGL` (Qt 6 removed `AA_DisableHardwareAcceleration`)
+
 ### Docs
 
 ## v1.0.1 (2026-08-22)

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "glint-monitor"
-version = "1.0.1"
+version = "1.0.2"
 description = "A Modern Painter-Rendered Desktop System Monitor"
 readme = "README.md"
 requires-python = ">=3.10"

src/app.py

@@ -2,13 +2,30 @@
 
 import sys
 
+from PyQt6.QtCore import Qt
 from PyQt6.QtWidgets import QApplication
 
+from src.core.compat import is_low_spec
 from src.ui.hud import GlassHUD
 from src.ui.tray import TrayManager
 
 
+def _maybe_disable_hardware_acceleration() -> None:
+    """Degrade the renderer on low-spec hosts before QApplication exists.
+
+    Must be called before ``QApplication`` is constructed, because on legacy
+    hardware the GPU/DWM recomposition of the translucent HUD causes
+    refresh/focus loops. Applied on every platform so behavior is consistent
+    regardless of the compositor or graphics stack in use.
+    """
+    if is_low_spec():
+        # Qt 6 removed AA_DisableHardwareAcceleration; AA_UseSoftwareOpenGL is
+        # its replacement and routes rendering through the software rasterizer.
+        QApplication.setAttribute(Qt.ApplicationAttribute.AA_UseSoftwareOpenGL)
+
+
 def main() -> int:
+    _maybe_disable_hardware_acceleration()
     app = QApplication(sys.argv)
     app.setApplicationName("Glint")
     app.setOrganizationName("ZFordDev")

src/core/compat.py

@@ -0,0 +1,54 @@
+"""Hardware capability detection for rendering fallbacks.
+
+Certain subsets of legacy Windows hardware trigger a DWM recomposition
+loop when the HUD's translucent, painter-rendered surface is refreshed on
+the GUI thread. Rather than forcing hardware acceleration off everywhere,
+we only degrade the renderer when the machine clearly falls below a
+generation threshold.
+"""
+
+from __future__ import annotations
+
+import logging
+
+import psutil
+
+logger = logging.getLogger(__name__)
+
+# A legacy profile: few logical cores plus modest physical memory. These
+# thresholds are intentionally conservative so modern machines keep
+# hardware-accelerated rendering and only clearly dated hardware falls back.
+LOW_CORE_THRESHOLD = 4
+LOW_RAM_THRESHOLD_BYTES = 8 * 1024**3  # 8 GiB
+
+
+def _logical_cores() -> int | None:
+    try:
+        count = psutil.cpu_count(logical=True)
+        return count if count else None
+    except (OSError, RuntimeError):
+        return None
+
+
+def _total_memory() -> int | None:
+    try:
+        return int(psutil.virtual_memory().total)
+    except (OSError, RuntimeError):
+        return None
+
+
+def is_low_spec() -> bool:
+    """Return True when the host is likely GPU-limited legacy hardware."""
+    cores = _logical_cores()
+    memory = _total_memory()
+    low_cores = cores is not None and cores <= LOW_CORE_THRESHOLD
+    low_memory = memory is not None and memory <= LOW_RAM_THRESHOLD_BYTES
+    if low_cores and low_memory:
+        logger.debug(
+            "Low-spec profile detected (cores=%s, ram=%s GiB); disabling hardware acceleration",
+            cores,
+            None if memory is None else round(memory / 1024**3, 1),
+        )
+        return True
+    logger.debug("Rendering profile: cores=%s, ram=%s", cores, memory)
+    return False

tests/test_core.py

@@ -165,3 +165,28 @@ def test_get_all_skips_heavy_probes_after_stop():
 
 def test_bundled_default_theme_loads():
     assert load_theme()["colors"]["text"]
+
+
+def test_low_spec_falls_back_when_cores_and_ram_are_legacy(monkeypatch):
+    from src.core import compat
+
+    monkeypatch.setattr(compat, "_logical_cores", lambda: 4)
+    monkeypatch.setattr(compat, "_total_memory", lambda: 6 * 1024**3)
+    assert compat.is_low_spec() is True
+
+
+def test_low_spec_requires_both_undersized_metrics(monkeypatch):
+    from src.core import compat
+
+    # Plenty of RAM but few cores -> not legacy enough to degrade rendering.
+    monkeypatch.setattr(compat, "_logical_cores", lambda: 2)
+    monkeypatch.setattr(compat, "_total_memory", lambda: 32 * 1024**3)
+    assert compat.is_low_spec() is False
+
+
+def test_low_spec_tolerates_missing_probes(monkeypatch):
+    from src.core import compat
+
+    monkeypatch.setattr(compat, "_logical_cores", lambda: None)
+    monkeypatch.setattr(compat, "_total_memory", lambda: None)
+    assert compat.is_low_spec() is False

tests/test_ui.py

@@ -77,3 +77,31 @@ def test_autostart_content_quotes_executable_paths(monkeypatch):
 
     monkeypatch.setattr("src.ui.tray.platform.system", lambda: "Darwin")
     assert f"<string>{spaced}</string>" in TrayManager._startup_content()
+
+
+def test_hardware_acceleration_disabled_when_low_spec(monkeypatch):
+    import src.app as app_module
+
+    calls = []
+    monkeypatch.setattr(app_module, "is_low_spec", lambda: True)
+    monkeypatch.setattr(
+        app_module.QApplication,
+        "setAttribute",
+        staticmethod(lambda attribute: calls.append(attribute)),
+    )
+    app_module._maybe_disable_hardware_acceleration()
+    assert calls == [app_module.Qt.ApplicationAttribute.AA_UseSoftwareOpenGL]
+
+
+def test_hardware_acceleration_kept_when_not_low_spec(monkeypatch):
+    import src.app as app_module
+
+    calls = []
+    monkeypatch.setattr(app_module, "is_low_spec", lambda: False)
+    monkeypatch.setattr(
+        app_module.QApplication,
+        "setAttribute",
+        staticmethod(lambda attribute: calls.append(attribute)),
+    )
+    app_module._maybe_disable_hardware_acceleration()
+    assert calls == []