Microsoft has pushed out yet another Redstone build to Fast ring Insiders, concentrating on fixing a load more bugs (though doubtless still not any of those we were complaining about - when are they going to get round to fixing the things people are most bothered by??) And there's a doozy or two in the known issues, which you'll want to note.

[Update] Microsoft has now pushed out 14379 - everything's as detailed below (including known issues), but with a couple of small fixes.

From Microsoft:

• We’re rolling out an Store update (11606.1001.25) that improves performance and reliability and includes fixes for accessibility as well.
• The Gadgets app has been updated to fix issues using it with a Microsoft Display Dock.
• We fixed an issue that could result in tiles pinned to Start from within an app being blank after a restore. We also fixed an issue that could result in multiple Live tiles no longer updating until the phone had been rebooted.
• We fixed an issue making it difficult to download certain offline maps via Settings > System > Offline maps, as the list would jump back to the top when you reached close to the bottom.
• We fixed an issue resulting in the Camera app intermittently freezing for a second when used in certain apps.
• We fixed an issue resulting in links no longer working in Microsoft Edge after exiting one-handed mode while a webpage is loading. We also fixed an issue where the enter key would act as if it had been pressed twice on some websites, resulting in two new lines being entered.
• We have improved the reliability of going between camera roll and Camera app.
• We fixed an issue where estimated time remaining for battery life under Settings > System > Battery could be clipped. We also improved performance of enumerating the list of apps in under Settings > System > Storage.
• We fixed an issue where the link in Cortana to download a speech language would open the Settings app homepage instead of going directly to Settings > Time and language > Language.
• We fixed an issue where the checkmarks in checkboxes in high contrast mode didn’t use the correct contrast ratio making them difficult to see.

As ever, there are some known issues for mobile, including a biggie relating to PDFs:

• You can open PDFs in Microsoft Edge but won’t be able to use touch to interact with the PDF (such as scrolling, pan or zoom). When you try to use touch to interact with a PDF, it will constantly reload the PDF.
• We’ve heard you and we are investigating decreases in battery life on older devices such as the Lumia 830, 930, and 1520.
• We’re also investigating Wi-Fi disconnect issues – if you are experiencing an issue with your Wi-Fi disconnecting, please see this forum post and make sure to upvote Wi-Fi disconnecting issues in the Feedback Hub.
• We have changed the backup format for Windows 10 Mobile devices to reduce the size of the backup stored in OneDrive. As a result, if you do a backup on a device running the latest Windows 10 Mobile Insider Preview builds and move back to the released version of Windows 10 Mobile (Build 10586) and restore from your backup – your Start screen layout won’t restore and remain the default Start layout. Your previous backup also gets overwritten. If you need to go back to Build 10586 temporarily, once you are on Build 10586 you should disable backup so it doesn’t overwrite the good backup from Windows 10 Mobile Insider Preview builds.

Also noteworthy is that the 'beta' Messaging service whereby the Cloud ws used to sync your text messages between devices is being discontinued. Sadly.

We have been testing with Windows Insiders a preview of the “Messaging everywhere” feature that allows you to receive and send text messages from your Windows 10 phone directly to and from your Windows 10 PC. The experience was well-received by Insiders however we believe we can deliver an even better experience through the Skype app. Because of this, we decided not to release this feature as part of the Windows 10 Anniversary Update this summer. Starting with Build 14376 and going forward, Insiders will no longer have the ability to reply to text messages from their phone via the Messaging app on their PCs. The ability to reply to text messages on your PC using Cortana is unaffected. Going forward, we will be working with the Skype Team on delivering a great “messaging everywhere” experience on your Windows 10 devices through the Skype app. We will share more details about this experience in the months ahead.

Argh - Why does Microsoft insist on continually trying to integrate SMS and Skype - it fails horribly every single time. Just keep 'em separate!!

My devices are updating as I write this. I'll report back, no doubt! The last build hasn't been without problems on the editorial devices here, but hey, this is the 'fast' ring for Insiders, so what do you expect?! I do maintain at least one device on the 'slow' ring too, so that I can monitor progress. Plus even more phones on the production builds.

Media controls continue to annoy me, plus that PDF bug will hit me hard, since I often use Edge for this purpose - I was half way through reading a 1000 page PDF ebook yesterday!

As per all my recent charts and comments, note that Redstone builds are NOT available for the non-Win-10-approved phones (e.g. Lumia 920). no matter how many times you install the 'Windows Insider' utility and enthusiastically tap the 'Fast ring' entry.... The highest version of Windows 10, even unsupported, for older (mainly x20) handsets is 'Threshold' ('the 10586.xxx branch, still being offered for a few more weeks under the 'Release Preview' ring). See my feature on all this if you're unsure where your phone will end up in Microsoft's roadmap.