gistfile1.m

// PTYTextView 27858

    if([self hasMarkedText]) {
        int len=[markedText length];
        if (len>WIDTH-x1) len=WIDTH-x1;
		NSRect inputFrame = NSMakeRect(floor(x1 * charWidth + MARGIN), (yStart + [dataSource numberOfLines] - HEIGHT) * lineHeight + (lineHeight - cursorHeight), ceil((WIDTH-x1)*cursorWidth),cursorHeight);
        [markedText drawInRect:inputFrame];
		NSAttributedString *attributedStringBeforeCursor = [markedText attributedSubstringFromRange:NSMakeRange(0, IM_INPUT_SELRANGE.location)	];
		NSRect spaceFrame = [attributedStringBeforeCursor boundingRectWithSize:inputFrame.size options:0];
		NSRect cursorFrame = NSMakeRect(inputFrame.origin.x + spaceFrame.size.width, inputFrame.origin.y, 2.0, inputFrame.size.height);
		[[NSColor redColor] set];
		NSRectFill(cursorFrame);
        
		memset([dataSource dirty] + yStart * WIDTH + x1, 
               1,
               WIDTH - x1 > len*2 ? len*2 : WIDTH-x1); //len*2 is an over-estimation, but safe
    }