When a second screen needs the same header as the first, you don't have to build it again. Copy the header container on one screen and paste it into the other: every control inside it comes along, with all its settings. You only rename the copies and change what's different.
Most canvas apps have more than one screen: a home screen, a list, a detail page. Adding one takes a couple of clicks in Power Apps Studio. The choice that matters is the layout, because some layouts come with controls already on them.
Focus isn't showing in the App checker means a control's focus border has a thickness of 0. Someone moving through the app with the keyboard can't see when they've landed on it. For anything they can tab to, give it a border; for a control they can't tab to, the border never appears anyway.
The App checker lists Missing tab stop under Accessibility errors: a control it considers interactive has no place in the keyboard's Tab order. For a gallery, the fix is TabIndex 0. For a plain heading, Microsoft's guidance points the other way, so think before you change it.
The App checker's Performance category shows Collection is initialized but never updated. A screen loads data into a collection and then only reads it. Collections are for data that changes in the app, so the checker suggests something lighter. Here's what it means and the two ways to fix it.
The App checker's Data source category shows a count, with the warning Unused data sources: This data source is not used in the app. Removing it will improve performance. It's telling the truth: no formula reads that data source yet. Whether to remove it depends on whether you're going to use it.
A yellow triangle appears next to a gallery, and the formula says Delegation warning. The "Filter" part of this formula might not work correctly on large data sets. The app still works today, but on a list with more than 500 items it will quietly miss some. The fix is to rewrite the part SharePoint can't run.
You select a gallery, insert a Text control, and it doesn't appear in the rows. It sits next to the gallery, outside it. With the gallery itself selected, Studio adds new controls beside it, not into its template. Select the template first.
You want a badge's color to follow its text, so you write Switch(Self.Content, ...) in its Intent. Studio underlines Content and says Name isn't valid. 'Content' isn't recognized. The modern Badge's text can't be read that way. Base the color on the same value the text comes from.
You set a label in a gallery to a SharePoint column, and instead of text you get a red error icon and Expected Text value. The column is a Choice column, and Power Apps gets a Choice as a record, not as text. Add .Value and it works.
