The test forces GraphicsBackend=opengl and builds a full MainWindow
with QOpenGLWidget-based viewer panels. On headless platforms whose
QPA cannot provide a GL context (Ubuntu/Windows CI on offscreen), the
app's GL calls crash on a non-current context (SEGFAULT in CI on
both). Probe with QOpenGLContext+QOffscreenSurface and GTEST_SKIP when
GL is unusable; the test still runs on platforms with real GL.
- all 19 panel classes: construction, titles, context/signal wiring,
save/load data round-trips
- MainWindowLayoutInfo XML round-trip, MainStatusBar, offscreen
MainWindow construction with standard panels and menus
- RatioDialog parsing (decimal and : / ; separators), validation
Mike-Solar