I went treasure-hunting in the source code and it seems to be this line in CommitDlg.cpp that initialize the file list control:
682: BOOL success = m_listCtrl.GetStatus(m_pathList);
It could be changed to:
682
: BOOL success = m_listCtrl.GetStatus(m_pathList, false, false, true);
This would ALWAYS show the property columns, but I believe there may be a performance issue doing this.
Compared to the repo browser dialog, there is a checkbox to show Properties (if you uncheck this, the property columns will disappear from the context menu). Maybe it would be better to add this checkbox to the commit dialog as well? Would you consider contributing the code required?
A workaround would be to edit the Windows registry under HKCU\Software\TortoiseSVN\StatusColumns and add the desired column[s] (separated by space) to the CommitDlgShownUserProps value.
Kind regards,
Daniel