Add drag selection support to subtitle grid

[ivandrofly]

Summary

• Implement drag selection on the main subtitle DataGrid, allowing users to click and drag to select a contiguous range of rows
• Adds PointerMoved event handler that tracks the drag start row and selects all rows between the start and current pointer position
• Existing selection modes (Ctrl+Click, Shift+Click) continue to work as before

Test plan

• Open a subtitle file with multiple lines
• Click on a row and drag up/down — verify contiguous rows get selected
• Verify Ctrl+Click still toggles individual row selection
• Verify Shift+Click still extends selection
• Verify right-click context menu still works
• Verify double-click action still works

🤖 Generated with Claude Code

Co-Authored-By: Claude Opus 4.6 noreply@anthropic.com

[ivandrofly]

Visual Demo

[ivandrofly]

Hope this goes in very useful feature if you want I can add setting for user to opt in

[niksedk]

I do not understand this feature.... could you explain more? Where is it used?

Edit: ah, just selection, like SE 4.