Fix: Fixate widget location in UiSettings frame

[TomBugnon]

Issue

When scrolling through data with the slider or using the Go To widget, the Settings frame size changes due to the varying length of the first row's text (Window : [...] || Scoring ...), which makes all the widgets in the panel move around a bit.

This forces the user to move the mouse before being able to click again on one of the widgets, or may resulte in slight forward scroll in the data when the user tries to backward scroll with the slider. (which are both annoying)

Fix

Use QGridLayout.addStretch rather than QGridLayout.addItem(QSpacerItem) to space items in the grid's first row

With this update, the widgets in the settings bar keep fixed locations during scrolling

[raphaelvallat]

Wonderful! All good to me 👍