On my form I have a tabpage with 6 tabs. In the modeler I can see only 4 the rest does not fit on the form. However they exist. To edit the right tab (tab 6) I have to 'move right' a number of tabs to be able to click on it and view the content of tab 6, Then, after editing I have to move it to the right again. Is there a way to see all tabs or to select one of them without moving them?
Increasing the canvas size (as suggested in the comments) can be used for this.
Select the page itself by clicking on the white area to the right of the content.
Increase the value of the 'Canvas width' property that you see in the property grid.
That should give the tab page names some more room.
Of course, it would be better if the tab widget in the Modeler dealt with this situation more elegantly. If you want, you can submit a ticket for that.