You can select various instruments and change drawing color.
Available instruments in this version:
-there are 2 modes of drawing: point-to-point (quicker) and real-time(slower)
You should to assign a key in settings to enter the drawing mode. After that you can use a "fire" button to draw or click on menus. The "alt fire" button calls the right-click menu. The first click shows possible colors, the second click - possible tools, the third click closes right-click menu.
To print text, click somewhere you want to print it, then change the letter with special keys (assign then in the menu). After that, just click to paste the letter. To end this, select the "END" symbol.
To quit from the drawing mode, press again the assigned button.
Tested on GZDoom 1.5.6