How Grid by Zaweba handles file types and Open with
Grid by Zaweba registers .zagr as its own file type and appears in Open with for .xlsx, .xls, .ods, .csv and .tsv without ever taking those types over.
Installing a new program shouldn't change what happens when you double-click your existing files. Grid by Zaweba follows that rule carefully. It claims one file type as its own and offers to open the others without taking anything over.
.zagr, Grid's own type
Grid registers .zagr as its own file type for the current Windows user. Double-click a .zagr file and it opens in Grid. That's the format for your working spreadsheets, and inside it's an .xlsx, so it holds formulas, styles, tables, conditional formats, validation, notes, charts and pictures, everything Grid can do.
Because a .zagr is an .xlsx inside, it's never a dead end. Save As .xlsx gives you a file most spreadsheet programs open, and even renaming a .zagr to .xlsx works.
Registering for the current user means the change is limited to your own Windows account. Other people on the same PC keep their own settings.
Other types: offered, never taken
For .xlsx, .xlsm, .xls, .ods, .csv and .tsv, Grid only adds itself to the Open with list. It never makes itself the default for those types. If you already have another spreadsheet, or a text editor set up for CSV, double-clicking those files carries on opening them exactly as before.
To open one in Grid, right-click the file, choose Open with and pick Grid. You can also open any of them from inside Grid with the usual Open command.
If you'd like Grid to become the default for a type, Windows lets you choose that yourself in the Open with dialog. That decision stays with you rather than with an installer.
Why it's done this way
Programs that grab every file type they can open cause real annoyance. A shared PC where one person installs a new app and everyone's spreadsheets suddenly open somewhere unfamiliar is a common story. Grid's approach avoids that, so trying it costs nothing: your existing setup is untouched, and Grid is there in Open with when you want it.
What each type means in practice
An .xlsx opens and saves with everything kept. An .xlsm, a workbook that contained macros, opens normally, but macros aren't run or kept, so it saves as .xlsx. An older .xls opens with its values as last saved, without the formulas. An .ods opens and saves with values, formulas, styles and more, though some richer features aren't written back. A .csv or .tsv opens with its encoding and delimiter detected.
A tidy way to work is to open whatever you're sent, save your own working copy as .zagr, and use Save As to send back the format the other person needs. Your folders then show at a glance which files are your working copies, since the .zagr ones open in Grid, while files you've received or exported keep their usual program.
The same split helps with backups and sharing. Keep the .zagr files as the masters you edit, and treat any .xlsx, .ods or CSV copies as things you made for someone else. If a copy goes astray or gets edited by another person, the master is still safe.
Grid also runs on macOS and Linux, sharing the same engine as the Windows version.
File types are a quiet part of any program. In Grid by Zaweba they're handled with restraint: one type of its own, and polite offers for the rest.
