mentalinstra, you have to choose a special project to build in that colony once all tiles are built on or you are done building.  Please let us know if you were building a special project and still got it stuck on idle colony.

If it is still stuck and reproducible please create a support ticket with the following information.

the console can be accessed by hitting the ~ key on your keyboard 

its located next to the 1 and between the esc and tab keys on most keyboards

its usefull for testing out many issues if you have a specific thing to test or sometimes in solving bugs or annoyances,

however it can also invalidate any testing you do to the game since the bugs you see may be caused by the commands you put in

some usefull commands

help    - this should list all the avaialable commands

turn    - this disables all the prompts that you normally would need to go through before ending your turn (research, ideology idle ship, idle colony, etc)

fow    - display's the entire map (this has been causing some problems on larger maps

You can also change the spending on your colony so it is not producing any manufacturing points. If you are not producing manufacturing points, then the game has no reason to make sure you spend it. Alternatively, you could shift all manufacturing points to the shipyard to produce ships. You can change the spendings of a planet independently of the empire spending, so the whole empire might be doing research except these planets.

No worries Mentalinstra and thanks for that accurate reply Seilore.

If all of your buildable hexes have been used up you can always use one of the projects that turns manufacturing points into something else, such as economy, research, etc. You will find these at the bottom of the project selection list with a duration of N/A (which just says that it will repeat forever until you change it or an automatic upgrade gets queued.). This can be quite useful if you need more BC for projects on other planets or on a shipyard.