我想到了两种方法……

Open another visual studio window and open the second solution in it. It would be preferable to add your existing projects to one solution, just right click and add existing project and navigate to the project file(csproj). .... e.g. C:\Users\User\Documents\Visual Studio 2012\Projects\MySqlWindowsFormsApplication1\MySql Windows Forms Project1\MySql Windows Forms Project1.csproj ....In this second way you might want to setup multiple start up projects i.e. for people with client-server apps or apps with dependencies. ....To do this Select the solution then GoTo: Project>>Properties>>Startup Project>> Select Multiple Startup projects and set actions to Start. When you debug, the selected as start will run. For interest sake you could open another multiple solution windows to view different projects at the same time. http://www.schwammysays.net/visual-studio-2012-tip-multiple-solution-explorers/

这就是Visual Studio的设计方式:一个解决方案，一个Visual Studio (VS)实例。

除了在一个VS实例中的解决方案之间切换之外，你还可以打开另一个VS实例，并用该实例打开你的另一个解决方案。正如你所说，解决方案旁边是“项目”。在一个解决方案中可以有多个项目，因此可以同时查看多个项目。

MAC users - this issue was winding me up, as its not possible to open two different Visual Studio instances at the same time. Ive found a solution that works fine, though its a little unorthodox : get the latest beta testing version, which will install alongside your normal VS install in a separate sandbox (it does this automatically). You can then run both versions side by side, which is enough for what I needed - to be able to examine one project for structure, code etc., while doing the actual coding I need to do in the 'current' VS install instance.

不知道这是否有用，但如果你想在多个项目中工作，而不需要在项目树中导航{像多窗口}，你可以尝试在另一个虚拟桌面中打开VS(至少在Windows 10中是可能的)，按住Ctrl+win+D。然后打开另一个VS工作室，在那里打开你的其他项目。您可以通过Ctrl+win+箭头键{左/右}在项目之间切换。

File ->新建窗口。在该窗口中选择另一个项目。每个项目都位于一个单独的窗口中。你可以在它们之间切换。

经过长期的研究和不同的实验，“MAC用户”最简单的方法是创建一个脚本:

open -a "Visual Studio" \
"path to first sln" \
"path to second sln" \
...

:D