I think your missing a step. After you execute the terminal command 'defaults write com.apple.dashboard devmode YES' you need to log out of your profile and log back in. I guess this serves to reset the dashboard. If you already tryed to move a widget onto your desktop from the dashboard simply log out and log back in and it should appear on your desktop.
That's my fault. I misunderstood your problem. The only time I've experianced an issue with disappearing widgets was when I first activated developer mode and I didn't know I had to log out and log back in. Doing so brought the widgets back to my desktop. I did however test my iMac running 10.8 ML just now by using developer mode to put 4 different widgets on my desktop and all of them were active at the same time. Mind you I'm not doing anything but looking at them. I leave all the developing to the real pros. I did however note when I first use developer mode to put a widget on my desktop I was unable to move it to any other desktop, ML allows multiple desktops, that being said when I use developer mode on a different desktop the widget always shows up on desktop #1 thus appearing to disapear from the desktop I'm working on.
I should probably have mentioned that I turned off separate desktop for widgets, but that may be self evident. Anyway, I don't seem to be able to find the desktop widget on any desktop when it disappears until I bounce Dashboard. Then it shows up on whatever desktop I'm using when I do the bouncing. Actually, I have an AppleScript that helps me with the bouncing, but I would still rather not have to run it. In the form I'm including, it just switches it on or off depending on it's current status, so I have to run it twice. It can be modified, of course, so that it turns Dashboard off then back on again in one execution. Anyway, I'm pretty sure I observed this issue on other Mountain Lion systems, but I need to double check. Thanks.
set _status to do shell script "defaults read com.apple.dashboard mcx-disabled"
if _status = "0" then
do shell script "defaults write com.apple.dashboard mcx-disabled -boolean YES"
tell application "Dock"
do shell script "defaults write com.apple.dashboard mcx-disabled -boolean NO"
tell application "Dock"
Message was edited by: llee (forgot to add script when first posted)
There are now (ML 10.8) two different Dashboards with different behavior.
And each Widget itself behave different (in developer mode) depending on to what kind of Dashboard it has been added to.
1st Any Widget that has been added to the "Space-Dashboard" must not been dragged in developer-mode. Neither at "Classic-Dashboard"-Mode nor in "Space-Dashboard"-mode. If you do so - it vanishes.
The only chance to reactivate it is to quit the dock either by (your) script, by terminal or using the Activity-Monitor-App. Otherwise you have to close it is to switch to "Space-Dashboard"-mode and to klick on Minus and you will see the (x) close-buttons from all the hidden invisible Widgets.
2nd Any Widget that should be usable in developer-mode should been added in the "Classic-Dashboard"-Mode. So first deselect "Show Dashboard as Space" in Mission Control settings. Then add the Widget in "Classic-Dashboard"-Mode. This time you can drag and drop the widget in developermode as well as in Snow Leopard without any Dock relaunch.
I think its a bug and not a feature.
Thanks for taking time to reply with this explanation. Maybe I'm misunderstanding part of it, but it still disappears when I perform the activate Dashboard,drag and hold,deactivate Dashboard, then release procedure even If I add the widget in "Classic-Dashboard". Turning off "Space-Dashboard" is all that's required to achieve "Classic-Dashboard", right?