Fix file rename: pre-fill dialog and actually delete old file

[saberoueslati]

Fixes #1034

Problem

Two bugs caused the rename feature (right-click tab → Rename) to misbehave:

1. Dialog opened with no pre-filled name. MainWindow::renameFile() passed only the default directory to FileDialogHelpers::getSaveFileName. QFileDialog only pre-fills the filename field when given a full file path, so the field was always empty.

2. Old file was never deleted. ScintillaNext::rename() checked if (saveCopyAs(newFilePath)) to decide whether to remove the original. saveCopyAs returns QFileDevice::FileError, where NoError == 0 (falsy). The condition was inverted — it entered the block only on error, so on success the QFile::remove was skipped and the old file was left on disk.

The combination made it appear as if the file was "renamed" in the tab but the original remained untouched and a second copy appeared at the destination.

Video of the manual test below :

Screencast.from.2026-05-02.00-56-33.webm

Changes

src/dialogs/MainWindow.cpp

Pass editor->getFilePath() (the current file's full path) to getSaveFileName instead of the default directory. QFileDialog now navigates to the file's directory and pre-fills its name.

src/ScintillaNext.cpp

Change the save-success check from if (saveCopyAs(newFilePath)) to if (saveCopyAs(newFilePath) == QFileDevice::NoError). The old file is now correctly removed after a successful copy.

[dail8859]

Awesome! Thank you!