Fix #7386: Measurement tooltip for tunnels, aqueducts & docks did not display or flickered.

Measurement tooltip was auto-closed as the hover/right-click test for tooltips was not
satisfied in this case. This is fixed by keeping the tooltip visible and instead explicitly
closing the tooltip when the PlaceObject is cancelled/completed.

src/misc_gui.cpp

@@ -724,8 +724,8 @@ struct TooltipsWindow : public Window
 		 * we are dragging the tool. Normal tooltips work with hover or rmb. */
 		switch (this->close_cond) {
 			case TCC_RIGHT_CLICK: if (!_right_button_down) delete this; break;
-			case TCC_LEFT_CLICK: if (!_left_button_down) delete this; break;
 			case TCC_HOVER: if (!_mouse_hovering) delete this; break;
+			case TCC_NONE: break;
 		}
 	}
 };

src/viewport.cpp

@@ -2508,12 +2508,17 @@ void UpdateTileSelection()
  * @param params (optional) up to 5 pieces of additional information that may be added to a tooltip
  * @param close_cond Condition for closing this tooltip.
  */
-static inline void ShowMeasurementTooltips(StringID str, uint paramcount, const uint64 params[], TooltipCloseCondition close_cond = TCC_LEFT_CLICK)
+static inline void ShowMeasurementTooltips(StringID str, uint paramcount, const uint64 params[], TooltipCloseCondition close_cond = TCC_NONE)
 {
 	if (!_settings_client.gui.measure_tooltip) return;
 	GuiShowTooltips(_thd.GetCallbackWnd(), str, paramcount, params, close_cond);
 }
 
+void HideMeasurementTooltips()
+{
+	DeleteWindowById(WC_TOOLTIPS, 0);
+}
+
 /** highlighting tiles while only going over them with the mouse */
 void VpStartPlaceSizing(TileIndex tile, ViewportPlaceMethod method, ViewportDragDropSelectionProcess process)
 {
@@ -2569,7 +2574,11 @@ void VpSetPresizeRange(TileIndex from, TileIndex to)
 	_thd.next_drawstyle = HT_RECT;
 
 	/* show measurement only if there is any length to speak of */
-	if (distance > 1) ShowMeasurementTooltips(STR_MEASURE_LENGTH, 1, &distance, TCC_HOVER);
+	if (distance > 1) {
+		ShowMeasurementTooltips(STR_MEASURE_LENGTH, 1, &distance);
+	} else {
+		HideMeasurementTooltips();
+	}
 }
 
 static void VpStartPreSizing()
@@ -3221,7 +3230,10 @@ void SetObjectToPlace(CursorID icon, PaletteID pal, HighLightStyle mode, WindowC
 		 * this function might in some cases reset the newly set object to
 		 * place or not properly reset the original selection. */
 		_thd.window_class = WC_INVALID;
-		if (w != NULL) w->OnPlaceObjectAbort();
+		if (w != NULL) {
+			w->OnPlaceObjectAbort();
+			HideMeasurementTooltips();
+		}
 	}
 
 	/* Mark the old selection dirty, in case the selection shape or colour changes */

src/window_gui.h

@@ -873,8 +873,8 @@ void RelocateAllWindows(int neww, int newh);
 /* misc_gui.cpp */
 enum TooltipCloseCondition {
 	TCC_RIGHT_CLICK,
-	TCC_LEFT_CLICK,
 	TCC_HOVER,
+	TCC_NONE,
 };
 
 void GuiShowTooltips(Window *parent, StringID str, uint paramcount = 0, const uint64 params[] = NULL, TooltipCloseCondition close_tooltip = TCC_HOVER);