Has anyone ever grown one of these plants indoors on a windowsill? I saw a potted pansy in a house window years ago, and often wonder how it did as a house plant.
If they are true annuals (?), you'd just need to replace them occasionally &/or start a succession of seeds to replace them yourself. With diligent deadheading, I wonder how long you could keep one going? If these plants also make cleistogamous seeds/flowers like ground violets, deadheading would be a moot point.
I think I increased the number of questions!
IMO, anything cheerful and bloom-ish that you have space for is great, even if it's temporary. Is there no space for them outside where you are?
I've grown pansies indoors, but never with the intention of keeping them as permanent indoor plants. Some years, I get impatient for spring and buy six-packs of them at the nurseries before it's warm enough to plant outside, so they live indoors for a few weeks. Other years, I've started these plants from seed indoors under lights, again with the intention of putting them out as soon as possible.
I didn't find them easy indoors, but that doesn't mean they can't be grown as houseplants. I believe they need cooler temperatures than are comfortable for most people, but if you have a spot where cyclamen do well, violas might do well there, too. In my experience, they need stronger light than cyclamen.
My issue, in particular with the nursery-grown plants, was that they seemed to be magnets for aphids and spider mites. I'm not sure one can buy these plants around here *without* aphids and spider mites. I had much less pest-trouble with the ones I grew from seed. I've found that the small-flowered, V tricolor types do better inside than the large-flowered pansy hybrids.
Outside, I dead-head mine and then, when they get stringy in the hot weather, I chop them back to about an inch above the ground. They sit there and do little until early fall, when they spring back to life and bloom until snow covers them. Sometimes I find them when the snow melts in spring, chop them back again, and get another season of bloom. I wonder if you could use the same chopping-back technique on an indoor plant, and maybe get a longer "season" out of it.
I think they'd make charming windowsill plants, If you try growing them inside, please let us know how it goes.