The black boxes appear because Krita is showing you the selection boundary, not a fill error

When you use the lasso selection tool in Krita and then fill that selection, the black boxes you see are the marching ants — the animated dashed line that marks your selection edge. They look like solid black rectangles when the selection is very small, zoomed in closely, or when you're using certain brush settings. This is normal behavior, not a bug or a problem with your fill.

The boxes disappear once you deselect the area. Press Select > None from the menu, or use the keyboard shortcut Shift + Ctrl + A (Windows) or Shift + Cmd + A (Mac). After you deselect, you'll see your actual filled shape without the selection outline.

Key Takeaways

  • The black boxes are the selection boundary (marching ants), not part of your actual artwork.
  • Deselecting the area removes the boxes and shows your real filled shape.
  • Zooming out or adjusting your view can make the selection outline less distracting while you work.
  • If black actually appears in your final image after deselecting, the issue is your brush or fill settings, not the lasso tool itself.

Why the selection outline looks like boxes instead of a smooth line

The marching ants animation in Krita uses small dashes to show where your selection edge is. When you zoom in very close — especially on a small selection — those dashes look like separate boxes rather than a continuous line. The effect is stronger if your selection has sharp corners or if you're working at high zoom levels.

This is how Krita (and most image editors like Photoshop and GIMP) displays selections by design. The dashed pattern helps you see the boundary clearly without it blending into your artwork. Zooming out slightly or panning away from the selection can make it feel less intrusive while you continue working.

What to check if black actually appears in your final image

If the black boxes remain after you deselect, or if black color shows up in your saved file, the problem is not the lasso tool — it's your fill settings. Check that your foreground color is not set to black before you fill. Click the foreground color square (usually in the left toolbar) and choose the color you actually want.

You should also verify that you're using the correct fill tool. The Bucket Fill Tool (shortcut Shift + B) fills a selection with solid color. The Fill with FG Color option under the Edit menu does the same thing. If you used a different tool or a filter, that could explain unexpected black areas. Undo your last action with Ctrl + Z (Windows) or Cmd + Z (Mac) and try again with the right tool and color.

How to work more comfortably with selections in Krita

If the marching ants distract you while you're filling or painting, you can hide them temporarily without losing the selection. Go to View > Show Selection to toggle the outline on and off. Your selection stays active even when the outline is hidden — you can still fill it or paint within it. Toggle the outline back on when you need to see where your selection is.

You can also adjust how the selection outline appears by changing your view zoom. Zoom out to see the full selection at once, which often makes the outline feel less like separate boxes. Use the scroll wheel or the View > Zoom menu to adjust your view without affecting your artwork.

Making cleaner lasso selections to avoid confusion

If you're making very small selections or selections with many sharp corners, the marching ants can become hard to read. Draw your lasso selection more slowly and deliberately to create smoother curves. Krita will simplify your path slightly, which can make the selection boundary clearer on screen.

You can also use the Select by Color Tool or the Fuzzy Select Tool (magic wand) if you're selecting areas of similar color — these tools often produce cleaner selection edges than the lasso, especially for detailed work. The lasso is best for freehand selections where you need precise control over the outline.

Frequently Asked Questions

How do I make the black boxes go away?

Press Select > None or use Shift + Ctrl + A to deselect. The marching ants outline will disappear immediately. If you want to hide the outline without losing the selection, use View > Show Selection to toggle it off.

Can I fill my selection without seeing the marching ants?

Yes. Use View > Show Selection to hide the outline, then fill your selection normally with the Bucket Fill Tool or Edit > Fill with FG Color. The selection stays active even though you can't see it. Toggle the outline back on afterward to verify your work.

Why does my filled area have actual black color in it after I deselect?

Your foreground color was set to black when you filled. Click the foreground color square in the toolbar and choose a different color. Undo the fill with Ctrl + Z, change your color, then fill again.

Is this a bug in Krita?

No. The marching ants selection outline is how all major image editors show selections. It's a standard feature, not an error. If you find it distracting, you can hide it with View > Show Selection while you work.