Allow click and dragging a view to drag the window itself?

Question

I\'m using a textured window that has a tab bar along the top of it, just below the title bar.

I\'ve used -setContentBorderThickness:forEdge: on the window to make t

Answer 1

If you got a NSTableView in your window, with selection enabled, overriding the mouseDownCanMoveWindow property won't work.

You need instead to create a NSTableView subclass and override the following mouse events (and use the performWindowDragWithEvent: mentioned in Dimitri answer):

@interface WindowDraggableTableView : NSTableView
@end

@implementation WindowDraggableTableView 
{
    BOOL _draggingWindow;
    NSEvent *_mouseDownEvent;
}

- (void)mouseDown:(NSEvent *)event
{
    if (self.window.movableByWindowBackground == NO) {
        [super mouseDown:event]; // Normal behavior.
        return;
    }

    _draggingWindow = NO;
    _mouseDownEvent = event;
}

- (void)mouseDragged:(NSEvent *)event
{
    if (self.window.movableByWindowBackground == NO) {
        [super mouseDragged:event]; // Normal behavior.
        return;
    }

    assert(_mouseDownEvent);
    _draggingWindow = YES;
    [self.window performWindowDragWithEvent:_mouseDownEvent];
}

- (void)mouseUp:(NSEvent *)event
{
    if (self.window.movableByWindowBackground == NO) {
        [super mouseUp:event]; // Normal behavior.
        return;
    }

    if (_draggingWindow == YES) {
        _draggingWindow = NO;
        return; // Event already handled by `performWindowDragWithEvent`.
    }

    // Triggers regular table selection.
    NSPoint locationInWindow = event.locationInWindow;
    NSPoint locationInTable = [self convertPoint:locationInWindow fromView:nil];
    NSInteger row = [self rowAtPoint:locationInTable];
    if (row >= 0 && [self.delegate tableView:self shouldSelectRow:row])
    {
        NSIndexSet *rowIndex = [NSIndexSet indexSetWithIndex:row];
        [self selectRowIndexes:rowIndex byExtendingSelection:NO];
    }
}

@end

Also don't forget to set the corresponding window movableByWindowBackground property as well:

self.window.movableByWindowBackground = YES;

Answer 2

It works for me after TWO steps:

1. Subclass NSView, override the mouseDownCanMoveWindow to return YES.
2. Subclass NSWindow, override the isMovableByWindowBackground to return YES.