I love the idea of having 1 Page that Players can always switch themselves to view, whenever they want, and then letting them switch back to the "current game map" (Player's Ribbon location). Of course you know Roll20 offers currently you can give a Handout to all players, with All Players edit permissions. Many of my groups use this. The players can Type their collective, collaborative notes. Unfortunately this method lacks the drag-and-drop pictures, and the Arrows drawing tool that you asked for. The API can do this. As a Roll20 PRO subscriber you can use the API scripts. There are Page-Manager / Map-Change API scripts available from the community. These basically offer a button that puts a MENU of links to Selected Pages in the Chat. Players are permissioned to be able to click a link and Go to that PAGE. As a Pro, with some setup work, you should be able to achieve your request for the most-part. When it comes to drag-and-drop pictures, there are limitations. The best workaround in the current system would be, you the GM drag-and-drop any pictures that they might want, set those pictures as Tokens assigned to All Players, now your Players will be able to move those pictures around, and draw arrows between them. There is another, somewhat obscure way, for Players to drag-and-drop a picture, it's very imperfect though. Create a Character called "Players Upload Pictures Here", and give that Character to All Players edit permission. Now a player can UPLOAD a pic to the Character's Avatar, and then drag-drop that character from the Journals tab. This will create a SQUARE SMALL UNPERMISSIONED token of that image on the whiteboard page. Yet another way is, Promote to Co-GM on all players. Since Co-GM's can drag-and-drop pictures and resize and give permission of them, and can also change the Player's Ribbon focus page. In most cases you don't want to do this because they get all the other GM powers! Drawing arrows and adding text notes is, already allowed to Players in default Roll20, once you overcome getting the Players to their Whiteboard page. In conclusion I like the suggestion of allowing 1 Whiteboard Page, or 1 Player-Accessible Page, or another approach would be allowing a HANDOUT to contain the features of a PAGE (such as pictures, and drawing arrows). Good idea.
