I found at the supermarket among the stationary stuff, a glue for kids which is waterbased and transparent, is like the white glue but colorless.
Since its waterbased can be wiped out with a wet cloth, and when dry its almost imperceptible...... dryes flat, so if some gets on the canopy its detectable and can be wiped out.
It can also be used on dioramas, sprayed to fix stuf to the ground, like leafs or rubble.
The brand i found is Resistol. Its colorless, odorless, and runs well.