Bug 425659

SUMMARY
It's a bit jarring to the user's experience to set up a filter layer for Random Noise and realize they'd have to hold on to the tiny arrow buttons or reach across the keyboard to type in a value they would like, especially when other filters (like HSL Adjustment and Gaussian Blur) and other parts of the interface (like Size/Flow/Opacity on the toolbar) don't act like this.

I will note the following filters (separated by their categories) that could use more sliders instead of pure text boxes:

Index Colors
Oil Paint
Pixelize
Posterize
Raindrops

Blur (this one also lacks a dial for configuring the angle)
Lens Blur (also lacks a dial)
Motion Blur (this one DOES have a dial though)

Gaussian High Pass

Emboss with Variable Depth

Gaussian Noise Reducer
Unsharp Mask
Wavelet Noise Reducer

Phong Bumpmap's Light Sources tab (has a dial for Azimuth but not one for Inclination)
Round Corners
Small Tiles

Random Noise
Random Pick
Wave

I would hope these would not be too troublesome to implement. Perhaps there could be an argument for sliders taking too much space in the UI, but most of these filters have a lot of empty space. If one were to configure them using the smaller window of Layer Properties, Gaussian Blur for example seems to have handled a smaller slider well enough.

I guess there's also an argument for slightly breaking existing workflows. For example, you can currently double left-click the Random Noise textboxes to type in your preferred value, but if it had a slider like Gaussian Blur, you'd have to right-click to manually type in your preferred value. However, I don't think this would be an issue at all if it used a Slider + Textbox combo like HSV Adjustment.