I don't know why I never asked this before in 20 years of using mIRC, but could we make scrolling possible while selecting buffer text for copy? None of the typical UI behaviors work.
Mouse Edge Scrolling -- Moving the mouse out of frame, above or below the text area, while holding the left-button down to select text, should automatically scroll the text buffer up or down at a reasonable rate. Rate of scroll speed might be increased with distance of mouse from frame edge.
Mouse Wheel Scrolling -- You can scroll with the mouse wheel while selecting text, however, currently the text selection routine is aborted and the selection is lost when moving the mouse wheel while selecting text with the left-button. Hopefully this can be a simple fix.
Keyboard Scrolling -- Using PgUp, PgDn, Ctrl+PgUp, Ctrl+PgDn will scroll the buffer, but as with the Mouse Wheel, the selection routine is aborted while attempting to do so. Hopefully this can be just as simple a fix.
Presently, the only way to copy multiple pages of text is to copy one page at a time, or to save and open the buffer log in notepad.
