More than one folder / project in one Sublime Text 3 window

You can accomplish this by saving your setups as a projects, then under project click switch project and all the tabs you saved in your workspace will appear

Open sublime Text 3, Inside menu bar

• Go to "Project"
• "Add folder to project..."

If by having multiple projects in one window you mean having multiple directories that are located in different places of your system at once in the sidebar tree, then yes, you can achieve this.

1. Open one of the projects in Sublime Text just like you always do.

2. Do one of the following:

   • Drag the root directory of the second project from the file explorer to the sidebar of the first project ST window.

   • In your terminal cd to the second project and enter subl . -a.

-a flag means to add to the last focused window instead of opening in a new window).

EDIT

Even easier solution.

Open the first project. Go to (in the menu above)

Project -> Add folder to project

If you're on a Mac just simply drag-&-drop your project folder/alias into Sublime Text Application on your dock.

Then you should see those projected loaded in your Sublime Text ready to go

Happy Coding !