Tab key can't be assigned to a shortcut

First of all, I know you're on vacation and that it's meant to be enjoyed. It's not urgent at all :).

It's not working as expected... but let's go step by step:

1_
I think I didn't express myself correctly. The word wasn't maximize, but restore.
The idea is for it to work like an on/off button.

2_
Your answer made me realize that you could also add a maximize function that would expand/restore the track height to the maximum height of the workspace. This would be useful when using Qtractor as an audio editor (I know it isn't, but... for many tasks I prefer it to Audacity).

3_
I tried implementing the minimize function... but, as always, C++ is too finicky for me. It doesn't accept setProperty like that, outright, as I'd like. However, the desired logic is as follows:

// Minimize current track height.
void qtractorMainForm::trackHeightMinimize (void)
{
	qtractorTrack *pTrack = nullptr;
	if (m_pTracks)
		pTrack = m_pTracks->currentTrack();
	if (pTrack == nullptr)
		return;

#ifdef CONFIG_DEBUG
	qDebug("qtractorMainForm::trackHeightMinimize()");
#endif

	const int iVerticalZoom = m_pSession->verticalZoom();

///////////////////// Changes

	const int iZoomTrackHeightMin = (iVerticalZoom * qtractorTrack::HeightMin) / 100;
	const int iZoomTrackHeightBase = (iVerticalZoom * qtractorTrack::HeightBase) / 100;	
	const int iZoomTrackHeightCurrent = (iVerticalZoom * pTrack->zoomHeight()) / 100;
	
	
	if (iZoomTrackHeightCurrent > iZoomTrackHeightMin) {
		pTrack->setProperty("RestoreHeightTo", iZoomTrackHeightCurrent);
		const int iZoomHeight = iZoomTrackHeightMin;
	}

	if (iZoomTrackHeightCurrent <= iZoomTrackHeightMin ){
		// To restore default to base, in case there is no previous height record
        	if (!ptrack->property("RestoreHeightTo").isValid()) {
			pTrack->setProperty("RestoreHeightTo", iZoomTrackHeightBase);
		}
		const int iZoomHeight =  pTrack->property("RestoreHeightTo");
	}


	m_pSession->execute(
		new qtractorResizeTrackCommand(pTrack, iZoomHeight));
}