QPlainTextEdit subclass function to indent lines in selection

I am, primarily for learning purposes, working on creating an editor component in C++ with Qt. As a first step, to begin getting familiar with editing a document via QTextCursor, I wrote this function on my subclass of QPlainTextEdit to indent multiple selected lines:

void MyEditor::increaseSelectionIndent()
{
    QTextCursor curs = textCursor();

    // Do nothing if we don't have a selection.

    if(!curs.hasSelection())
        return;

    // Get the first and count of lines to indent.

    int spos = curs.anchor(), epos = curs.position();

    if(spos > epos)
    {
        int hold = spos;
        spos = epos;
        epos = hold;
    }

    curs.setPosition(spos, QTextCursor::MoveAnchor);
    int sblock = curs.block().blockNumber();

    curs.setPosition(epos, QTextCursor::MoveAnchor);
    int eblock = curs.block().blockNumber();

    // Do the indent.

    curs.setPosition(spos, QTextCursor::MoveAnchor);

    curs.beginEditBlock();

    for(int i = 0; i <= (eblock - sblock); ++i)
    {
        curs.movePosition(QTextCursor::StartOfBlock, QTextCursor::MoveAnchor);

        curs.insertText("\t");

        curs.movePosition(QTextCursor::NextBlock, QTextCursor::MoveAnchor);
    }

    curs.endEditBlock();

    // Set our cursor's selection to span all of the involved lines.

    curs.setPosition(spos, QTextCursor::MoveAnchor);
    curs.movePosition(QTextCursor::StartOfBlock, QTextCursor::MoveAnchor);

    while(curs.block().blockNumber() < eblock)
    {
        curs.movePosition(QTextCursor::NextBlock, QTextCursor::KeepAnchor);
    }

    curs.movePosition(QTextCursor::EndOfBlock, QTextCursor::KeepAnchor);

    // Done!

    setTextCursor(curs);
}

I'm interested in any feedback on whether or not I'm following "best practices" with QTextCursor - am I doing anything weird, or that can be simplified or improved?

-
Some of these comments can be removed:

Too obvious:

// Do nothing if we don't have a selection.

Noisy:

// Done!

-
These initialized variables:

int spos = curs.anchor(), epos = curs.position();

should be on separate lines for better maintenance:

int spos = curs.anchor();
int epos = curs.position();

-
No need to do a manual swap:

if(spos > epos)
{
    int hold = spos;
    spos = epos;
    epos = hold;
}

Just use std::swap to keep it idiomatic:

if (spos > epos)
{
    std::swap(spos, epos);
}

-
No need calculate the difference each time:

for(int i = 0; i <= (eblock - sblock); ++i)

Define a constant before the loop and use it instead:

const int blockDifference = eblock - sblock;

for (int i = 0; i <= blockDifference; ++i)

StackExchange Code Review Q#33899, answer score: 6