I would find this useful. YMMV.

It seems like the OnHover-method in the veghicle_gui.cpp can only be executed by hovering over the vehicle in the viewport and not by hovering over any other widgets.

The problem is caused by the DispatchHoverEvent method in the window.cpp; In case a tooltip is defined the OnHover-method is not executed.

Possible fix: Remove the return statement from the tooltip handling;

static void DispatchHoverEvent(Window *w, int x, int y)
{
	NWidgetCore *wid = w->nested_root->GetWidgetFromPos(x, y);

	/* No widget to handle */
	if (wid == nullptr) return;

	Point pt = { x, y };

	/* Show the tooltip if there is any */
	if (!w->OnTooltip(pt, wid->index, TCC_HOVER) && wid->tool_tip != 0) {
		GuiShowTooltips(w, wid->tool_tip);
        DEBUG(misc,1,"STOPED BY TOOLTIP: %d",wid->index);
        return;
	}

	/* Widget has no index, so the window is not interested in it. */
	if (wid->index < 0) return;

	DEBUG(misc,1,"DispatchHoverEvent: %d",wid->index);

	w->OnHover(pt, wid->index);
}

So I tried commenting out the return statement and compiling the code again. Unforunately, nothing really changed.

I then activated "enable-debug" from "configure" and recompiled the project and stepped through the code. Being previously not familiar with the code, I stepped into the OnHover() function, which we can arrive at now, since the return statement in the tooltip handler is commented out, and it took me to the following empty virtual function.

	/**
	 * The mouse is hovering over a widget in the window, perform an action for it.
	 * @param pt     The point where the mouse is hovering.
	 * @param widget The widget where the mouse is hovering.
	 */
	virtual void OnHover(Point pt, int widget) {}
....

I grepped for "OnHover" in the OpenTTD project and found no additional references, calls, definitions, etc. I was hoping the debugger got it wrong and I would find a reimplementation of the OnHover function in some subclass. I didn't.

So, this might be a naive question on my part (I haven't delved into the code for more than a couple of days), but what is the purpose of an empty virtual function with no reimplementation in any other class.

Because of the possibility of use! Or perhaps it was used in the past and has since been removed

Ok. So if I understand it correctly, I can reimplement this OnHover function in "some class" in such a way, that upon hovering the mouse in the vehicle window on the widget showing "Stopped"/"Stopping",etc, it would show the destination. I am not sure, where exactly would be appropriate to place that function, but I look into it.

Yes, just like the other On* functions

@junaidnaseer you can implement OnHover for each window (here the vehicle_window); There you have to switch-case base on the widget type (see OnClick Method). In my experiments i was not able to identify how to implement the proposed behavior without further reworking of the widgets.

Ok, guys thanks for the tips. I am looking into the OnClick method in the vehicle_gui.cpp file and see how I can implement something ... as a first step anything that shows any change from the current behavior.

If that works, my second step would be to try to implement the above mentioned feature, if possible.

@junaidnaseer What do you mean with "anything that shows any change from the current behavior"? I would rather recommand to first get the changing of the text working, i.e., change the text in the START_STOP based OnHover and revert the changes after stop hovering. To build the right message-string for the bar should be done afterwards.

By "anything that shows any change from the current behavior", I meant I would try to write a reimplementation of the OnHover function, in way that I can see some other text in the widget, where it is written "Stopped"/"Waiting ...".

Ok, so I reimplemented the OnHover function and I can see through the debugger that upon hovering over the widget containing the text "Stopped"/"Waiting", I do enter my OnHover function. I have hit a couple of roadblocks here.

1. Where exactly does the output of the macro DEBUG() go to? Is it written in some log file? I don't see the output in the console. I didn't see any log file under /tmp either. I wanted to check the "vehstatus" but the debugger kept showing "value optimized out" while the log file, I could not find.

		DEBUG(misc, 6, "Vehicle state, %d", v->vehstatus);

2. I was able to:

...
			SetDParam(0, v->current_order.GetDestination());
			SetDParam(1, v->GetDisplaySpeed());
			str = STR_VEHICLE_STATUS_HEADING_FOR_STATION_VEL;
...

But I am not sure where exactly to pass this str string further to update the widget text. In the DrawWidget function, I see a function DrawString. I am not sure, but maybe I have to use the DrawWidget or the DrawString function somehow.

Try DEBUG(misc, 0, ...) or increase debug level to >=6 else the message won't be shown.