problem is propably identical to this forum post about NB6.7:
When i tried to open project properties of a freeform or nbandroid project, nothing seemed to happen:
no dialog popping up, and focus was still on the main netbeans window.
For "regular" Java Project types like "java se" and "java me" everything worked normal, i.e. the properties window appeared as expected.
I use my laptop display in combination with an external display.
Because of changing workspaces, the external monitor sits sometimes "to the right" and sometimes "to the left" of the laptop display.
Netbeans seems to "remember" the position the dialog was on before, even if that position is not visible with the current display configuration.
As soon as I "switched positions" of my displays, the missing dialogs appeared on the display that did not contain the main netbeans window.
I suppose Netbeans needs to check the position of Dialogs to make sure they are valid in the current display setup.
Marking as a duplicate of issue 187608 as there is more information in that issue. This is common to the generic project UI API support. See issue 187608 for more details.
*** This bug has been marked as a duplicate of bug 187608 ***