Replace COptionMenu with juce::PopupMenu

[baconpaul]

The juce API is more robust. Over the summer go through and replace the escape_from_vstgui COptionMenu with juce::PopupMenu. This issue tracks the menus we have to do as checklists

• Scene copy paste (so we have a worked example)
• The param RMB
• All the rest

[baconpaul]

Alright so here is a short guide for 'how to replace a COptionMenu with a juce::PopupMenu'
This assumes that you aren't doing any funny business (like custom renderers or anything)
Also you mostly have to do an all-or-nothing on a menu so tackling SGE could be work

but basically VSTGUI looks like

auto a = new COptionMenu()
auto b = new CCOmmandMenuItem(); b.setCallback([](){}); a->addItem(b)

that second part we often wrap in a little lambda called 'addCallbackFunction'. Then we have to forget things at the right time, add them to the frame, and force a show.

With juce popup menus we don't actually have to do most of that. A simple juce popup menu example would be

auto contextMenu = juce::PopupMenu();
contextMenu.addItem("Say Hi", []() { std::cout << "Hi" << std::endl; });
contextMenu.addItem("Say Bye", []() { std::cout << "Bye" << std::endl; });
contextMenu.addSeparator();
contextMenu.addItem( "Say Why", []() {std::out << "Why" << std::endl; });

contextMenu.showMenuAsync(juce::PopupMenu::Options());

and that will show the 3 element menu.

The full documentation is https://docs.juce.com/master/classPopupMenu.html but you will see things like multiple instances of addItem. For instance addItem( "Whatzit", false, true, [](){} ); will be not enabled (first bool) and ticked (second).

Adding a submenu is similarly easy. You use addSubMenu( String, PopupMenu ) method. So something like this

auto contextMenu = juce::PopupMenu();

auto hiBye = juce::PopupMenu();
hiBye.addItem("Say Hi", []() { std::cout << "Hi" << std::endl; });
hiBye.addItem("Say Bye", []() { std::cout << "Bye" << std::endl; });
contextMenu.addSubMenu("HiBye", hiBye);
contextMenu.addItem( "Say Why", []() {std::out << "Why" << std::endl; });

contextMenu.showMenuAsync(juce::PopupMenu::Options());

which would give you

HiBye >
    Say Hi
    Say Bye
SayWhy

Right now JUCE menus can't put checkmarks on parent submenus. If you come across a case where you have to do that put a FIXME in the code and I'll fix it once I have that fixed. I know how to fix it and it is easy enough change (basically just a quick subclass).

As a first try I would recommend making the OSC copy and paste menu (around line 1930 of SGE) and convert that. Then try a few of the MSEGs. Once we have it down we can push through and get the rest of them.