Configure the option "Set left and first-line indent with Tab and Backspace keys" (File | Options)

Here you can configure if the user can indent/unindent paragraphs with the Tab and Backspace keys.

Supported on: At least Windows Vista
Registry HiveHKEY_LOCAL_MACHINE or HKEY_CURRENT_USER
Registry PathSOFTWARE\Policies\SoftMaker\TextMaker 2018
Value NameIndentParagraphsWithTab
Value TypeREG_DWORD
Enabled Value1
Disabled Value0

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