MIDI range MKII (extracted from microtonal PR) (#5868)

* Update MIDI range to match MIDI specification

Co-authored-by: IanCaio <iancaio_dev@hotmail.com>
Co-authored-by: Kevin Zander <veratil@gmail.com>
Co-authored-by: Hyunjin Song <tteu.ingog@gmail.com>
Co-authored-by: Spekular <Spekular@users.noreply.github.com>

data/themes/classic/style.css

@@ -165,9 +165,11 @@ PianoRoll {
 	qproperty-whiteKeyInactiveTextColor: rgb( 128, 128, 128);
 	qproperty-whiteKeyInactiveTextShadow: rgb( 240, 240, 240 );
 	qproperty-whiteKeyInactiveBackground: qlineargradient(x1:0, y1:0, x2:1, y2:0, stop:0 #eeeeee, stop:1 #ffffff);
+	qproperty-whiteKeyDisabledBackground: qlineargradient(x1:0, y1:0, x2:1, y2:0, stop:0 #a0a0a0, stop:1 #b0b0b0);
 	qproperty-blackKeyWidth: 48;
 	qproperty-blackKeyActiveBackground: qlineargradient(x1:0, y1:0, x2:1, y2:0, stop:0 #43e97b, stop:1 #3bcd6c);
 	qproperty-blackKeyInactiveBackground: qlineargradient(x1:0, y1:0, x2:1, y2:0, stop:0 #333, stop:1 #000);
+	qproperty-blackKeyDisabledBackground: qlineargradient(x1:0, y1:0, x2:1, y2:0, stop:0 #606060, stop:1 #505050);
 	/* Grid colors */
 	qproperty-lineColor: rgba( 128, 128, 128, 80 );
 	qproperty-beatLineColor: rgba( 128, 128, 128, 160 );

data/themes/default/style.css

@@ -197,9 +197,11 @@ PianoRoll {
 	qproperty-whiteKeyInactiveTextColor: #000;
 	qproperty-whiteKeyInactiveTextShadow: #fff;
 	qproperty-whiteKeyInactiveBackground: qlineargradient(x1:0, y1:0, x2:1, y2:0, stop:0 #eeeeee, stop:1 #ffffff);
+	qproperty-whiteKeyDisabledBackground: qlineargradient(x1:0, y1:0, x2:1, y2:0, stop:0 #a0a0a0, stop:1 #b0b0b0);
 	qproperty-blackKeyWidth: 48;
 	qproperty-blackKeyActiveBackground: qlineargradient(x1:0, y1:0, x2:1, y2:0, stop:0 #43e97b, stop:1 #3bcd6c);
 	qproperty-blackKeyInactiveBackground: qlineargradient(x1:0, y1:0, x2:1, y2:0, stop:0 #333, stop:1 #000);
+	qproperty-blackKeyDisabledBackground: qlineargradient(x1:0, y1:0, x2:1, y2:0, stop:0 #606060, stop:1 #505050);
 	/* Grid colors */
 	qproperty-lineColor: #292929;
 	qproperty-beatLineColor: #2d6b45;