Check out this blog post from Linus (http://world.episerver.com/Blogs/Linus-Ekstrom/Dates/2012/9/EPiServer-7-Configuring-editors-for-your-properties/) and shout if you have more questions.
Ben is right. Legacy editors require posting back to update editing value, which does not very well fit into the Sparrowhawk style. However, if you don't bother with an ugly Save button, you could definitely make it. I have created an experimental inline editor for LinkCollectionList properties a few months back. You can try at your risk.
Thanks, a new editor did the trick! :-)
We hade upgraded a project from EpiServer 6 R2 to Episerver 7. The project contains a custom property that simply prints out a divider (an underlined heading) used to group properties in edit mode.
After the upgrade to EpiServer 7 the custom property were displayed as a regular textbox. I added a UIHint (not connected to any editor) ([UIHint("UseLegacyEditorForDivider")]) and now I get the property displayed as:
"Click button to edit property" (translated from norwegian) - and when I click the button I can finally se my divider.
Is it possible to have the divider displayed "inline" - so it can be seen without clicking the button?