Bug 473246

SUMMARY
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The "Random Noise" filter layer is not working properly.
The are the noise is applied is not defined properly and changes when hiding and showing the filter layer.
The inherit alpha option of the filter layer doesn´t affect the area.
Flattening the noise filter transforms the layer into a paint layer, but it's transparency still hides the layers below in the same group.

After many tests, it seems when flattening the noise filter layer, it doesn´t show updates to layers below when inside a group, all becomes normal after the layer is moved again.
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STEPS TO REPRODUCE
1. Create a new document
2. Fill the document with a clear color and random lines of a different color (this will help verify noise and transparency later)
3. Create a new paint layer.
4. Select a square area and fill with another clear color, unselect the area.
5. Select the layer containing the painted square and create a group.
6. Add a "Random Noise filter" layer with Level 50 over the layer with the square inside the group.
7. VERIFY: the are of the filter layer is incorrect and changes when hiding or showing the filter layer.
8. Hide the painted layer with the lines and the painted layer with the square.
9. Flatten the noise filter layer.
10. Show both painted layers
11. VERIFY: The painted layer outside the group is visible, but the painted layer inside the group and below the filter layer isn´t
12. VERIFY: Move the flattened filter layer (now a paint layer) to verify it has transparency
13. Hide the flattened filter layer
14. VERIFY: the layer containing the square and inside the group becomes visible (this happens even with more than one paint layer inside the group).
15. Show the flattened filter layer and turn on it's inherit alpha option.
16. Paint something on the layer with the square.
17. VERIFY: the layer with the square is still hidden and changes aren't visble.
17. Move the flattened filter layer.
18. VERIFY: now the layer with the square becomes visible and works as expected.
19. VERIFY: further changes in the square layer become visible.


OBSERVED RESULT
The filter layer doesn´t affect only the area of the painted layers below ( as is the case of the "Halftone" layer for example, which works ok).


EXPECTED RESULT
The Noise filter layer should affect only the areas of painted layers below (or the alpha lock should do)
After flattening the Noise filter layer, transparency of the flattened layer shouldn´t hide the layers below in the same group.


SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Ubuntu 22.04.3 LTS

ADDITIONAL INFORMATION