YOffset attribute in Manual section cannot have negative value

[eturpault]

The attributes YOffset_KEYTYPE and Key999YOffset can be set at a value from 0 to 500. Negative Y offset value is not possible.
This doesn't permit to display correctly keyboards sharp keys of some Hauptwerk sample sets.

For example with the Prytanée sample set of Sonus Paradisi :
keyboard (on the left the expected display, on the right the obtained display with YOffset=0 instead of -10) :

pedal (on the left the expected display, on the right the obtained display with YOffset=0 instead of -56) :

Same issue with for example Buckeburg and Noordbroek sample sets of Sonus Paradisi.

Could the YOffset accepted range be extented to negative values : -100 for example ?

[eturpault]

Thanks @oleg68 for the implementation, I confirm that the keys can now be all displayed as expected with the sample sets that I tested.