Theme Visibility Issues: Invisible Overflow Button (Dark) and Low-Contrast Markers (Light)

[ThomasMalletCodra]

Describe the bug

Several UI elements have poor visibility depending on the selected theme (dark or light), making them difficult or impossible to use.

1. Dark theme: Toolbar overflow button is invisible

When using the dark theme on a small screen, the toolbar shortcut buttons next to the image/plot area may not all fit in the available space. A small overflow button with two arrows (») appears to access the hidden buttons. However, this button is rendered as a black icon on a black background, making it completely invisible. The button is only discoverable by hovering over its location by chance.

2. Light theme: Yellow marker cursors have poor contrast

In the light theme, the annotation/marker cursors are displayed in yellow, which provides very poor contrast against the white/light background. The markers are difficult to see. In contrast, the dark theme displays markers in yellow on a dark background, which works well.

There does not appear to be a user-accessible setting to change the marker cursor color.

To Reproduce

Dark theme — invisible overflow button

1. Open DataLab with the dark theme enabled
2. Use a small screen or resize the window so that the toolbar buttons next to the plot do not all fit
3. Look for the overflow button (double arrow ») that should appear at the bottom/end of the toolbar
4. Observe that the button is invisible (black on black) — only visible when hovering

Light theme — poor marker contrast

1. Open DataLab with the light theme enabled
2. Create or import a signal and add annotation markers
3. Observe that the yellow marker cursors are barely visible against the light background

Expected behavior

Dark theme

The toolbar overflow button should use a visible icon color (e.g., white or light gray) that contrasts with the dark background.

Light theme

Marker cursors should use a color that provides good contrast against a light background (e.g., dark blue, dark red, or black). Alternatively, the marker color should automatically adapt to the current theme. Ideally, users should also be able to configure the marker color.

Screenshots

Installation information

• Reported by external user
• Observed on standard DataLab installation

Additional context

• Affected components:
  • Overflow button visibility: Qt stylesheet / guidata toolbar theming
  • Marker colors: PlotPy cursor/marker rendering defaults