Fix incorrect Slider value label position

[jorgenherje]

Slider value label is positioned incorrectly when sliding through values. Jumps high when thumb is not on/near a specific tick/mark on the slider. When the mouse/thumb is near the tick, the label moves to correct position. Position is incorrect through slider movement.

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See video. When no markers/ticks, the label is positioned incorrect all the time. If ticks/markers are available, the label is correctly places when thumb/mouse is on tick/maker:

20241029-1344-57.8552466.mp4