feat(gioui): + and - keys add/subtract elements in tables

Closes #65.

CHANGELOG.md

@@ -19,6 +19,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Massive rewrite of the GUI, in particular allowing better copying, pasting and
   scrolling of table-based data (order list and note data).
 - Dbgain unit, which allows defining the gain in decibels (-40 dB to +40dB)
+- `+` and `-` keys add/subtract values in order editor and pattern editor
+  ([#65][i65])
 
 ### Fixed
 - 32-bit su_load_gmdls clobbered ebx, even though __stdcall demands it to be not
@@ -140,6 +142,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 [0.3.0]: https://github.com/vsariola/sointu/compare/v0.2.0...v0.3.0
 [0.2.0]: https://github.com/vsariola/sointu/compare/v0.1.0...v0.2.0
 [0.1.0]: https://github.com/vsariola/sointu/compare/4klang-3.11...v0.1.0
+[i65]: https://github.com/vsariola/sointu/issues/65
 [i112]: https://github.com/vsariola/sointu/issues/112
 [i116]: https://github.com/vsariola/sointu/issues/116
 [i120]: https://github.com/vsariola/sointu/issues/120

tracker/gioui/scroll_table.go

@@ -123,8 +123,8 @@ func (s *ScrollTableStyle) handleEvents(gtx layout.Context) {
 			key.Filter{Focus: s.ScrollTable, Name: "C", Required: key.ModShortcut},
 			key.Filter{Focus: s.ScrollTable, Name: "V", Required: key.ModShortcut},
 			key.Filter{Focus: s.ScrollTable, Name: "X", Required: key.ModShortcut},
-			key.Filter{Focus: s.ScrollTable, Name: ",", Required: key.ModShift},
-			key.Filter{Focus: s.ScrollTable, Name: ".", Required: key.ModShift},
+			key.Filter{Focus: s.ScrollTable, Name: "+"},
+			key.Filter{Focus: s.ScrollTable, Name: "-"},
 		)
 		if !ok {
 			break
@@ -291,10 +291,12 @@ func (s *ScrollTable) command(gtx C, e key.Event) {
 		s.Table.SetCursorX(0)
 	case key.NameEnd:
 		s.Table.SetCursorX(s.Table.Width() - 1)
-	case ".":
+	case "+":
 		s.Table.Add(1)
-	case ",":
+		return
+	case "-":
 		s.Table.Add(-1)
+		return
 	}
 	if !e.Modifiers.Contain(key.ModShift) {
 		s.Table.SetCursor2(s.Table.Cursor())