Make dataset description text selectable

[cdebonnel]

Problem

A dataset description may contain example inputs for users to copy in a text field of the dataset. However, the dataset description is not selectable by mouse, preventing easy copying.

Proposal

Add a per-item flag to dataset items so that the description can be made selectable when desired.

Solution

Add a per-item flag (selectable_description: bool = False) to dataset item definitions. When True, render the description widget with Qt.TextSelectableByMouse. Default remains False for backward compatibility.

Alternatives

A non-editable TextItem may be used to display a selectable text or a new widget created through subclassing and setting of appropriate Qt flag.

[PierreRaybaut]

Issue Resolved ✅

Thank you for this excellent feature request! You're absolutely right that dataset description text should be selectable to allow copying example inputs and code snippets.

What was implemented
I've implemented a simple and effective solution that makes all dataset comment text selectable by adding the Qt.TextSelectableByMouse flag to the QLabel widgets that display dataset comments.

Changes made:

• Modified qtwidgets.py to enable text selection on dataset comment labels
• This affects both tabbed dataset dialogs and single dataset edit widgets
• No API changes required - existing code continues to work unchanged

Why this approach
Rather than adding a per-item flag as originally proposed, we determined that:

• Dataset comments are dataset-level, not item-level - they appear as a single text block above all items
• No backward compatibility concerns - making text selectable doesn't change appearance, behavior, or APIs
• Simpler is better - users now get the copy functionality without needing to configure anything

Result
Users can now:
✅ Select and copy text from dataset descriptions using mouse selection
✅ Copy example inputs, code snippets, configuration values, etc.
✅ Use existing datasets without any changes required

This enhancement improves usability for technical documentation scenarios while maintaining full backward compatibility.