In my TextPad preferences "Allow multiple instances to run" is unchecked. The other day, I noticed that I had two instances of TextPad running. After this happened a few times, I realized why:
It looks like starting with TextPad 7.5.0, the context menu now has two options for TextPad:
Open with TextPad
Open in existing TextPad session >
I hadn't noticed the new Open in existing TextPad session option because I was so used to just right clicking and moving up the Open with TextPad option. If TextPad is configured to not allow multiple instances, should the context menu just have the one "Open with TextPad" option which would open the file in the existing instance of TextPad?
I just updated to TextPad 7.5.1 (32 bit version) and the context menu still has both options. Is this intentional in the case where only one instance of TextPad is allowed? It just makes it take a little longer to open a file not normally associated with TextPad because you have to deliberately select the current instance off of the sub menu.
This seems to be a bug that was introduced with the "New Explorer context menu command to open a file in a particular instance" enhancement in TextPad 7.5.0 (14-May-2015).
Unchecking the TexPad preference "Allow multiple instances to run" should require that "Open with TextPad" context menu option always use the existing session. The "Open in existing TextPad session" context menu option should be removed as only one instance should be allowed.
Good news: In TextPad 7.6, with "Allow multiple instances to run" unchecked, the "Open with TextPad" context-menu item re-uses a running instance. Thanks, Helios, for fixing this!
I can confirm that if you install TextPad 8.0 and 7.6 in that order and then select the Context Menu option in v8.0, the Open in TextPad command does not work. A workaround is to uninstall both editions of TextPad and then reinstall 7.6 first.
Before doing that, uncheck the Context Menu option and close all instances of Explorer, so that a restart won't be necessary to delete ShellExt64.dll.