Mouse cursor invisible over canvas when Move Selected Pixels tool is active (NVIDIA/X11/GTK4)

[linuxlite]

Mouse cursor invisible over canvas when Move Selected Pixels tool is active (NVIDIA/X11/GTK4)

Description

When using the Move Selected Pixels tool, the mouse cursor becomes completely invisible over the canvas. All other tools display the cursor correctly.

Steps to Reproduce

1. Launch Pinta on Linux with NVIDIA GPU and X11
2. Open or create an image
3. Select the Move Selected Pixels tool (M)
4. Move the mouse over the canvas

Expected Behaviour

Cursor should be visible over the canvas.

Actual Behaviour

Cursor is completely invisible over the canvas. It reappears when moving off the canvas onto other UI elements.

Environment

• Pinta 3.1.2 (built from source)
• GTK4 4.22.2
• GPU: NVIDIA GeForce RTX 5060 Ti
• Driver: 595.71.05
• DE: XFCE / X11
• OS: Linux Lite 8.0 (Ubuntu 26.04)

Root Cause

In Pinta.Tools/Tools/MoveSelectedTool.cs, DefaultCursor is defined as:

public override Gdk.Cursor DefaultCursor => Gdk.Cursor.NewFromTexture (Resources.GetIcon (Pinta.Resources.Icons.ToolMoveCursor), 0, 0, null);

The null fallback cursor passed to NewFromTexture causes GTK4 to render an invisible cursor on NVIDIA/X11, where the hardware cursor plane cannot composite a custom texture cursor without a valid fallback.

Fix

Replace null with Gdk.Cursor.NewFromName("default", null) as the fallback:

public override Gdk.Cursor DefaultCursor => Gdk.Cursor.NewFromTexture (Resources.GetIcon (Pinta.Resources.Icons.ToolMoveCursor), 0, 0, Gdk.Cursor.NewFromName ("default", null));

This should also be audited across all other tools that pass null as the fallback to NewFromTexture.

[cameronwhite]

The Gdk.Cursor docs state If none of the provided cursors can be supported, the default cursor will be the ultimate fallback so I'm surprised that this is necessary.
Have you tested the suggested change and verified that it works, or was this an AI suggestion?

[linuxlite]

The change is tested and working, unsure of the relevance of A.I. here. Patched on my machine with:

sed -i 's/Gdk.Cursor.NewFromTexture (Resources.GetIcon (Pinta.Resources.Icons.ToolMoveCursor), 0, 0, null)/Gdk.Cursor.NewFromTexture (Resources.GetIcon (Pinta.Resources.Icons.ToolMoveCursor), 0, 0, Gdk.Cursor.NewFromName ("default", null))/' ~/pinta-3.1.2/Pinta.Tools/Tools/MoveSelectedTool.cs

[cameronwhite]

Thanks! The formatting of the bug report was similar to some LLM-generated ones I've gotten so I was just checking.

[linuxlite]

You're welcome @cameronwhite

[badcel]

Is this an upstream issue?

[cameronwhite]

Yeah I'm wondering that .. I wasn't able to reproduce it testing on an Ubuntu 26.04 VM

[linuxlite]

Did you try Linux Lite 8.0 ?

[cameronwhite]

Not yet, I haven't set up a VM for that yet