Annotation labels overlap and marker display settings have no effect

[ThomasMalletCodra]

Describe the bug

Two issues have been identified with the annotation and marker display system:

1. Overlapping annotation labels

When two or more annotations (markers) are positioned on a curve at nearby locations, the intersection point value labels overlap and become unreadable. There is currently no way to reposition or offset the labels to make all values visible.

2. Marker display settings have no visible effect

The marker parameter dialog (accessible via the plot context menu) exposes two line style options: "Line (not selected)" and "Line (selected)" . Changing the colors or styles for these settings (e.g., setting one to green and the other to red) and closing the dialog has no visible effect on the marker appearance. The marker rendering does not reflect any changes made through this settings window.

To Reproduce

Overlapping labels

1. Open DataLab and create or import a signal (e.g., a Gaussian curve)
2. Add two annotations (markers) positioned at nearby X coordinates on the curve
3. Observe that the intersection point value labels overlap and cannot be read

Marker settings ineffective

1. Right-click on a marker to open the marker parameters dialog
2. Change the line color for "Trait (hors sélection)" to green and "Trait (sélection)" to red
3. Close the settings dialog
4. Observe that the marker appearance has not changed

Expected behavior

Overlapping labels

Annotation labels should either:

• Be automatically offset to avoid overlapping, or
• Be displayed in movable text boxes that the user can drag to a readable position

Marker settings

Changes made to the marker display parameters (line color, style for selected/unselected states) should be immediately reflected on the plot markers.

Screenshots

Two annotation markers on a Gaussian with overlapping value labels:

Marker parameter configuration dialog (changes have no effect):

Installation information

• Reported by external user
• Observed on standard DataLab installation

Additional context

• Affected component: PlotPy (marker/annotation rendering)
• Related code: plotpy marker and annotation item classes
• The "Line (not selected)" / "Line (selected)" labels in the settings dialog are also unclear — their purpose and expected behavior should be documented