#296 TaurusWheel unusable if squeezed vertically

[Carlos Pascual]

To reproduce:

• taurusform sys/tg_test/1/{long,double, float}_scalar
• Change the write widget of one of the rows to TaurusWheelEdit
• Reduce the vertical size of the form as much as possible

the arrows will block the numbers, or the numbers will become unreadable

This affects at least v3.7.1 and 4.0.0