Right now it's not too bad, and next release I will be able to clear out all the WW1WF missions that are spamming the list. However, I can see that list eventually becoming unwieldy as the number of available missions increase over the years.
Right now you have two checkbox "All Terrains" and "Only Missions You Created" to filter. I'd suggest a refinement that would offer more flexibility and better precision.
I'd change both of those to combobox. The first entry in each combobox would be the "All" case. The remaining combobox list items would be the specific filters.
i.e. First combobox something like:
[*All Terrains]
CraterMA
Euro2015
Rift Valley
etc...
Second combobox like:
[*All Designers]
Arlo
CptTrips
Greebo
Buster
etc...
The two filter combobox selections would be additive.
$0.02,
CptTrips
