I want at least a warning when I try to open the same solution twice. In VB 2008 I several times overwrote some of my own new code because of lack of this. In VB 2010 and 11 this is better - you get warning if the code is changed and may update - but still I want a clear warning when I try to open the solution the second time. In VB6 you are not able to open it twice. (Sometimes you do want to be able to open it a second time to have a look at how the code where before you made your change - so a combination would be the best solution - a warning (so you know it is already open) but then you may open it a second time.)