- negative scale and line width is not sensible and lead to strange effects thus set a minimum
- set the minimum reasonably above 0 since e.g. a hatch scale of 0.01 fills 8 GB RAM -> out of RAM error
- disable KeyboardTracking since we don't want a time-consuming recomputation while the user changes a value
- fix dialog layout (was broken for Windows) and simplify it
- enable so immediately the changes you make in the dialog -> necessary to fine-tune the right position