Last week, Microsoft launched its latest Windows 10 Mobile Insider Preview, showcasing the various improvements made to the OS ahead of the release of the Creators Update in the coming months. But as build 15025 rolled out, many were concerned by the continued absence of several key features which had previously been announced, but which still haven't shown up in recent previews.

That's led to growing speculation that Microsoft may have delayed some features, or that it may not intend to bring certain features to its mobile OS at all. These include improvements to Continuum, which were originally revealed at its Ignite conference in September, along with more recent additions like Night Light, which has appeared on recent desktop builds of Windows 10.

In an interview with Neowin at Microsoft's NexTech Africa conference, Dona Sarkar, chief of the Windows Insider Program, told me that features like these haven't been dropped, and are still being lined up for Windows 10 Mobile.

"They're not in the builds yet," Dona explained. "We're still trying to figure out when is the right time for them to be in the builds." She added:

We do know that these features are very important, so we want to unveil them at the right time for the audience... For us, it's all about the quality. We don't want to add features when we don't love the quality of the build yet, so we'd rather focus on building up quality than figuring out when to roll features.

Given the limited time available between now and when the Creators Update is expected to arrive - according to Dell, it will begin rolling out to Windows 10 devices in April - I asked Dona if that might result in a longer wait for the Windows 10 Mobile version of the update to arrive. After all, these features need time to be tested by Insiders - and the number of Windows 10 Mobile users who also have Continuum-enabled handsets makes up only a very small proportion of the 400 million Windows 10 devices now in use.

She said: "We would never ship to Insiders without giving it enough 'runway' to get the feedback... That's the point of Insiders, right? That's why we roll things to Insiders so early. A lot of times, Insiders actually get mad; like, "This isn't quite ready for prime time." And we're like, "no it's not, that's the point!"

But when I asked her more pointedly about when to expect features like Night Light on Windows 10 Mobile, she added:

We have to figure out timelines, right? We have to see first, how does that feature do on desktop? And if the feedback is good, we're like, okay, yeah - that seems like a good idea for Mobile as well. But if the feature doesn't get the kind of feedback that we need to say, okay, yeah, that's a feature that people love, that they're using, we're getting data on, then we wouldn't expand it to Mobile. What we don't like to do is pull things out.

Dona also noted that features like Night Light are still being actively developed, based directly on feedback from Insiders using those features on desktop, right down to the name: "A lot of people said 'Blue Light's a dumb name; we don't like this, it makes no sense'. We said, 'Actually, you're right, Insiders!' - and that [name change to Night Light] was a direct result of feedback from Insiders."

Even a seemingly trivial change like switching the name of a minor feature, or simply fixing a tiny bug, requires extensive revisions and checks across the OS, demanding considerable time and resources in the development process. Dona explained:

Okay, say I fix a bug in Night Light, that seems to be surface-level; even changing its name. If we didn't replace every example of that, everywhere in code, there'd be some big disaster. And it's not just a 'find and replace', because often it's like, we called it this thing, and we took a dependency on that and used it to instantiate this other thing - and suddenly, we've broken the kernel of Windows. I've done this, so I know. Trust me - I have done this! I've thought, 'oh, this is a little UX change, this is not going to be a big deal'. Took down the graphics stack. I've done this. So I know - I get a phone call when that happens...!

Of course, the question of exactly when these new features will make it to the Mobile OS - even in preview form - remains unanswered. But the rumored death of Windows 10 Mobile simply isn't on the cards, as far as Dona is concerned.

"The future of Windows 10 Mobile is that we're continuing to invest in Mobile," she said. "We're definitely going towards more 'let's help you be as productive as possible with this device in your pocket that you have all the time on you'. We roll builds every week [to internal or external rings], we push features, we do the thing; it's a thing that we continue to invest in, just like all device families."

Stay tuned to Neowin later this week when you can watch my full video interview with Dona Sarkar, discussing a range of topics, after about two hours of sleep, with the aid of alcohol, and despite being hindered by technical glitches...