03-18-2017, 12:17 PM
Untick the "Rounded corners" in the Tool options dialog.
To make this setting stick, see Edit>Preferences>Tool options: save the options when you leave Gimp, or set the options permanently to always start Gimp with the same settings ("Save options now!" and uncheck "Save options on exit".
To make this setting stick, see Edit>Preferences>Tool options: save the options when you leave Gimp, or set the options permanently to always start Gimp with the same settings ("Save options now!" and uncheck "Save options on exit".